chore: regens API reference docs (#889)

diff --git a/docs/dyn/bigtableadmin_v2.projects.instances.clusters.html b/docs/dyn/bigtableadmin_v2.projects.instances.clusters.html
index 9d7771d..94b553d 100644
--- a/docs/dyn/bigtableadmin_v2.projects.instances.clusters.html
+++ b/docs/dyn/bigtableadmin_v2.projects.instances.clusters.html
@@ -75,7 +75,12 @@
 <h1><a href="bigtableadmin_v2.html">Cloud Bigtable Admin API</a> . <a href="bigtableadmin_v2.projects.html">projects</a> . <a href="bigtableadmin_v2.projects.instances.html">instances</a> . <a href="bigtableadmin_v2.projects.instances.clusters.html">clusters</a></h1>
 <h2>Instance Methods</h2>
 <p class="toc_element">
-  <code><a href="#create">create(parent, body, clusterId=None, x__xgafv=None)</a></code></p>
+  <code><a href="bigtableadmin_v2.projects.instances.clusters.backups.html">backups()</a></code>
+</p>
+<p class="firstline">Returns the backups Resource.</p>
+
+<p class="toc_element">
+  <code><a href="#create">create(parent, body=None, clusterId=None, x__xgafv=None)</a></code></p>
 <p class="firstline">Creates a cluster within an instance.</p>
 <p class="toc_element">
   <code><a href="#delete">delete(name, x__xgafv=None)</a></code></p>
@@ -90,18 +95,18 @@
   <code><a href="#list_next">list_next(previous_request, previous_response)</a></code></p>
 <p class="firstline">Retrieves the next page of results.</p>
 <p class="toc_element">
-  <code><a href="#update">update(name, body, x__xgafv=None)</a></code></p>
+  <code><a href="#update">update(name, body=None, x__xgafv=None)</a></code></p>
 <p class="firstline">Updates a cluster within an instance.</p>
 <h3>Method Details</h3>
 <div class="method">
-    <code class="details" id="create">create(parent, body, clusterId=None, x__xgafv=None)</code>
+    <code class="details" id="create">create(parent, body=None, clusterId=None, x__xgafv=None)</code>
   <pre>Creates a cluster within an instance.
 
 Args:
-  parent: string, The unique name of the instance in which to create the new cluster.
+  parent: string, Required. The unique name of the instance in which to create the new cluster.
 Values are of the form
-`projects/<project>/instances/<instance>`. (required)
-  body: object, The request body. (required)
+`projects/{project}/instances/{instance}`. (required)
+  body: object, The request body.
     The object takes the form of:
 
 { # A resizable group of nodes in a particular cloud location, capable
@@ -110,7 +115,7 @@
   "defaultStorageType": "A String", # (`CreationOnly`)
       # The type of storage used by this cluster to serve its
       # parent instance's tables, unless explicitly overridden.
-  "serveNodes": 42, # The number of nodes allocated to this cluster. More nodes enable higher
+  "serveNodes": 42, # Required. The number of nodes allocated to this cluster. More nodes enable higher
       # throughput and more consistent performance.
   "state": "A String", # (`OutputOnly`)
       # The current state of the cluster.
@@ -118,13 +123,13 @@
       # The location where this cluster's nodes and storage reside. For best
       # performance, clients should be located as close as possible to this
       # cluster. Currently only zones are supported, so values should be of the
-      # form `projects/<project>/locations/<zone>`.
-  "name": "A String", # (`OutputOnly`)
+      # form `projects/{project}/locations/{zone}`.
+  "name": "A String", # Required. (`OutputOnly`)
       # The unique name of the cluster. Values are of the form
-      # `projects/<project>/instances/<instance>/clusters/a-z*`.
+      # `projects/{project}/instances/{instance}/clusters/a-z*`.
 }
 
-  clusterId: string, The ID to be used when referring to the new cluster within its instance,
+  clusterId: string, Required. The ID to be used when referring to the new cluster within its instance,
 e.g., just `mycluster` rather than
 `projects/myproject/instances/myinstance/clusters/mycluster`.
   x__xgafv: string, V1 error format.
@@ -137,64 +142,35 @@
 
     { # This resource represents a long-running operation that is the result of a
       # network API call.
+    "response": { # The normal response of the operation in case of success.  If the original
+        # method returns no data on success, such as `Delete`, the response is
+        # `google.protobuf.Empty`.  If the original method is standard
+        # `Get`/`Create`/`Update`, the response should be the resource.  For other
+        # methods, the response should have the type `XxxResponse`, where `Xxx`
+        # is the original method name.  For example, if the original method name
+        # is `TakeSnapshot()`, the inferred response type is
+        # `TakeSnapshotResponse`.
+      "a_key": "", # Properties of the object. Contains field @type with type URL.
+    },
     "metadata": { # Service-specific metadata associated with the operation.  It typically
         # contains progress information and common metadata such as create time.
         # Some services might not provide such metadata.  Any method that returns a
         # long-running operation should document the metadata type, if any.
       "a_key": "", # Properties of the object. Contains field @type with type URL.
     },
+    "done": True or False, # If the value is `false`, it means the operation is still in progress.
+        # If `true`, the operation is completed, and either `error` or `response` is
+        # available.
+    "name": "A String", # The server-assigned name, which is only unique within the same service that
+        # originally returns it. If you use the default HTTP mapping, the
+        # `name` should be a resource name ending with `operations/{unique_id}`.
     "error": { # The `Status` type defines a logical error model that is suitable for # The error result of the operation in case of failure or cancellation.
         # different programming environments, including REST APIs and RPC APIs. It is
-        # used by [gRPC](https://github.com/grpc). The error model is designed to be:
+        # used by [gRPC](https://github.com/grpc). Each `Status` message contains
+        # three pieces of data: error code, error message, and error details.
         #
-        # - Simple to use and understand for most users
-        # - Flexible enough to meet unexpected needs
-        #
-        # # Overview
-        #
-        # The `Status` message contains three pieces of data: error code, error
-        # message, and error details. The error code should be an enum value of
-        # google.rpc.Code, but it may accept additional error codes if needed.  The
-        # error message should be a developer-facing English message that helps
-        # developers *understand* and *resolve* the error. If a localized user-facing
-        # error message is needed, put the localized message in the error details or
-        # localize it in the client. The optional error details may contain arbitrary
-        # information about the error. There is a predefined set of error detail types
-        # in the package `google.rpc` that can be used for common error conditions.
-        #
-        # # Language mapping
-        #
-        # The `Status` message is the logical representation of the error model, but it
-        # is not necessarily the actual wire format. When the `Status` message is
-        # exposed in different client libraries and different wire protocols, it can be
-        # mapped differently. For example, it will likely be mapped to some exceptions
-        # in Java, but more likely mapped to some error codes in C.
-        #
-        # # Other uses
-        #
-        # The error model and the `Status` message can be used in a variety of
-        # environments, either with or without APIs, to provide a
-        # consistent developer experience across different environments.
-        #
-        # Example uses of this error model include:
-        #
-        # - Partial errors. If a service needs to return partial errors to the client,
-        #     it may embed the `Status` in the normal response to indicate the partial
-        #     errors.
-        #
-        # - Workflow errors. A typical workflow has multiple steps. Each step may
-        #     have a `Status` message for error reporting.
-        #
-        # - Batch operations. If a client uses batch request and batch response, the
-        #     `Status` message should be used directly inside batch response, one for
-        #     each error sub-response.
-        #
-        # - Asynchronous operations. If an API call embeds asynchronous operation
-        #     results in its response, the status of those operations should be
-        #     represented directly using the `Status` message.
-        #
-        # - Logging. If some API errors are stored in logs, the message `Status` could
-        #     be used directly after any stripping needed for security/privacy reasons.
+        # You can find out more about this error model and how to work with it in the
+        # [API Design Guide](https://cloud.google.com/apis/design/errors).
       "message": "A String", # A developer-facing error message, which should be in English. Any
           # user-facing error message should be localized and sent in the
           # google.rpc.Status.details field, or localized by the client.
@@ -206,22 +182,6 @@
         },
       ],
     },
-    "done": True or False, # If the value is `false`, it means the operation is still in progress.
-        # If `true`, the operation is completed, and either `error` or `response` is
-        # available.
-    "response": { # The normal response of the operation in case of success.  If the original
-        # method returns no data on success, such as `Delete`, the response is
-        # `google.protobuf.Empty`.  If the original method is standard
-        # `Get`/`Create`/`Update`, the response should be the resource.  For other
-        # methods, the response should have the type `XxxResponse`, where `Xxx`
-        # is the original method name.  For example, if the original method name
-        # is `TakeSnapshot()`, the inferred response type is
-        # `TakeSnapshotResponse`.
-      "a_key": "", # Properties of the object. Contains field @type with type URL.
-    },
-    "name": "A String", # The server-assigned name, which is only unique within the same service that
-        # originally returns it. If you use the default HTTP mapping, the
-        # `name` should have the format of `operations/some/unique/name`.
   }</pre>
 </div>
 
@@ -230,8 +190,8 @@
   <pre>Deletes a cluster from an instance.
 
 Args:
-  name: string, The unique name of the cluster to be deleted. Values are of the form
-`projects/<project>/instances/<instance>/clusters/<cluster>`. (required)
+  name: string, Required. The unique name of the cluster to be deleted. Values are of the form
+`projects/{project}/instances/{instance}/clusters/{cluster}`. (required)
   x__xgafv: string, V1 error format.
     Allowed values
       1 - v1 error format
@@ -257,8 +217,8 @@
   <pre>Gets information about a cluster.
 
 Args:
-  name: string, The unique name of the requested cluster. Values are of the form
-`projects/<project>/instances/<instance>/clusters/<cluster>`. (required)
+  name: string, Required. The unique name of the requested cluster. Values are of the form
+`projects/{project}/instances/{instance}/clusters/{cluster}`. (required)
   x__xgafv: string, V1 error format.
     Allowed values
       1 - v1 error format
@@ -273,7 +233,7 @@
     "defaultStorageType": "A String", # (`CreationOnly`)
         # The type of storage used by this cluster to serve its
         # parent instance's tables, unless explicitly overridden.
-    "serveNodes": 42, # The number of nodes allocated to this cluster. More nodes enable higher
+    "serveNodes": 42, # Required. The number of nodes allocated to this cluster. More nodes enable higher
         # throughput and more consistent performance.
     "state": "A String", # (`OutputOnly`)
         # The current state of the cluster.
@@ -281,10 +241,10 @@
         # The location where this cluster's nodes and storage reside. For best
         # performance, clients should be located as close as possible to this
         # cluster. Currently only zones are supported, so values should be of the
-        # form `projects/<project>/locations/<zone>`.
-    "name": "A String", # (`OutputOnly`)
+        # form `projects/{project}/locations/{zone}`.
+    "name": "A String", # Required. (`OutputOnly`)
         # The unique name of the cluster. Values are of the form
-        # `projects/<project>/instances/<instance>/clusters/a-z*`.
+        # `projects/{project}/instances/{instance}/clusters/a-z*`.
   }</pre>
 </div>
 
@@ -293,9 +253,9 @@
   <pre>Lists information about clusters in an instance.
 
 Args:
-  parent: string, The unique name of the instance for which a list of clusters is requested.
-Values are of the form `projects/<project>/instances/<instance>`.
-Use `<instance> = '-'` to list Clusters for all Instances in a project,
+  parent: string, Required. The unique name of the instance for which a list of clusters is requested.
+Values are of the form `projects/{project}/instances/{instance}`.
+Use `{instance} = '-'` to list Clusters for all Instances in a project,
 e.g., `projects/myproject/instances/-`. (required)
   pageToken: string, DEPRECATED: This field is unused and ignored.
   x__xgafv: string, V1 error format.
@@ -315,7 +275,7 @@
         "defaultStorageType": "A String", # (`CreationOnly`)
             # The type of storage used by this cluster to serve its
             # parent instance's tables, unless explicitly overridden.
-        "serveNodes": 42, # The number of nodes allocated to this cluster. More nodes enable higher
+        "serveNodes": 42, # Required. The number of nodes allocated to this cluster. More nodes enable higher
             # throughput and more consistent performance.
         "state": "A String", # (`OutputOnly`)
             # The current state of the cluster.
@@ -323,17 +283,17 @@
             # The location where this cluster's nodes and storage reside. For best
             # performance, clients should be located as close as possible to this
             # cluster. Currently only zones are supported, so values should be of the
-            # form `projects/<project>/locations/<zone>`.
-        "name": "A String", # (`OutputOnly`)
+            # form `projects/{project}/locations/{zone}`.
+        "name": "A String", # Required. (`OutputOnly`)
             # The unique name of the cluster. Values are of the form
-            # `projects/<project>/instances/<instance>/clusters/a-z*`.
+            # `projects/{project}/instances/{instance}/clusters/a-z*`.
       },
     ],
     "failedLocations": [ # Locations from which Cluster information could not be retrieved,
         # due to an outage or some other transient condition.
         # Clusters from these locations may be missing from `clusters`,
         # or may only have partial information returned.
-        # Values are of the form `projects/<project>/locations/<zone_id>`
+        # Values are of the form `projects/&lt;project&gt;/locations/&lt;zone_id&gt;`
       "A String",
     ],
   }</pre>
@@ -354,14 +314,14 @@
 </div>
 
 <div class="method">
-    <code class="details" id="update">update(name, body, x__xgafv=None)</code>
+    <code class="details" id="update">update(name, body=None, x__xgafv=None)</code>
   <pre>Updates a cluster within an instance.
 
 Args:
-  name: string, (`OutputOnly`)
+  name: string, Required. (`OutputOnly`)
 The unique name of the cluster. Values are of the form
-`projects/<project>/instances/<instance>/clusters/a-z*`. (required)
-  body: object, The request body. (required)
+`projects/{project}/instances/{instance}/clusters/a-z*`. (required)
+  body: object, The request body.
     The object takes the form of:
 
 { # A resizable group of nodes in a particular cloud location, capable
@@ -370,7 +330,7 @@
   "defaultStorageType": "A String", # (`CreationOnly`)
       # The type of storage used by this cluster to serve its
       # parent instance's tables, unless explicitly overridden.
-  "serveNodes": 42, # The number of nodes allocated to this cluster. More nodes enable higher
+  "serveNodes": 42, # Required. The number of nodes allocated to this cluster. More nodes enable higher
       # throughput and more consistent performance.
   "state": "A String", # (`OutputOnly`)
       # The current state of the cluster.
@@ -378,10 +338,10 @@
       # The location where this cluster's nodes and storage reside. For best
       # performance, clients should be located as close as possible to this
       # cluster. Currently only zones are supported, so values should be of the
-      # form `projects/<project>/locations/<zone>`.
-  "name": "A String", # (`OutputOnly`)
+      # form `projects/{project}/locations/{zone}`.
+  "name": "A String", # Required. (`OutputOnly`)
       # The unique name of the cluster. Values are of the form
-      # `projects/<project>/instances/<instance>/clusters/a-z*`.
+      # `projects/{project}/instances/{instance}/clusters/a-z*`.
 }
 
   x__xgafv: string, V1 error format.
@@ -394,64 +354,35 @@
 
     { # This resource represents a long-running operation that is the result of a
       # network API call.
+    "response": { # The normal response of the operation in case of success.  If the original
+        # method returns no data on success, such as `Delete`, the response is
+        # `google.protobuf.Empty`.  If the original method is standard
+        # `Get`/`Create`/`Update`, the response should be the resource.  For other
+        # methods, the response should have the type `XxxResponse`, where `Xxx`
+        # is the original method name.  For example, if the original method name
+        # is `TakeSnapshot()`, the inferred response type is
+        # `TakeSnapshotResponse`.
+      "a_key": "", # Properties of the object. Contains field @type with type URL.
+    },
     "metadata": { # Service-specific metadata associated with the operation.  It typically
         # contains progress information and common metadata such as create time.
         # Some services might not provide such metadata.  Any method that returns a
         # long-running operation should document the metadata type, if any.
       "a_key": "", # Properties of the object. Contains field @type with type URL.
     },
+    "done": True or False, # If the value is `false`, it means the operation is still in progress.
+        # If `true`, the operation is completed, and either `error` or `response` is
+        # available.
+    "name": "A String", # The server-assigned name, which is only unique within the same service that
+        # originally returns it. If you use the default HTTP mapping, the
+        # `name` should be a resource name ending with `operations/{unique_id}`.
     "error": { # The `Status` type defines a logical error model that is suitable for # The error result of the operation in case of failure or cancellation.
         # different programming environments, including REST APIs and RPC APIs. It is
-        # used by [gRPC](https://github.com/grpc). The error model is designed to be:
+        # used by [gRPC](https://github.com/grpc). Each `Status` message contains
+        # three pieces of data: error code, error message, and error details.
         #
-        # - Simple to use and understand for most users
-        # - Flexible enough to meet unexpected needs
-        #
-        # # Overview
-        #
-        # The `Status` message contains three pieces of data: error code, error
-        # message, and error details. The error code should be an enum value of
-        # google.rpc.Code, but it may accept additional error codes if needed.  The
-        # error message should be a developer-facing English message that helps
-        # developers *understand* and *resolve* the error. If a localized user-facing
-        # error message is needed, put the localized message in the error details or
-        # localize it in the client. The optional error details may contain arbitrary
-        # information about the error. There is a predefined set of error detail types
-        # in the package `google.rpc` that can be used for common error conditions.
-        #
-        # # Language mapping
-        #
-        # The `Status` message is the logical representation of the error model, but it
-        # is not necessarily the actual wire format. When the `Status` message is
-        # exposed in different client libraries and different wire protocols, it can be
-        # mapped differently. For example, it will likely be mapped to some exceptions
-        # in Java, but more likely mapped to some error codes in C.
-        #
-        # # Other uses
-        #
-        # The error model and the `Status` message can be used in a variety of
-        # environments, either with or without APIs, to provide a
-        # consistent developer experience across different environments.
-        #
-        # Example uses of this error model include:
-        #
-        # - Partial errors. If a service needs to return partial errors to the client,
-        #     it may embed the `Status` in the normal response to indicate the partial
-        #     errors.
-        #
-        # - Workflow errors. A typical workflow has multiple steps. Each step may
-        #     have a `Status` message for error reporting.
-        #
-        # - Batch operations. If a client uses batch request and batch response, the
-        #     `Status` message should be used directly inside batch response, one for
-        #     each error sub-response.
-        #
-        # - Asynchronous operations. If an API call embeds asynchronous operation
-        #     results in its response, the status of those operations should be
-        #     represented directly using the `Status` message.
-        #
-        # - Logging. If some API errors are stored in logs, the message `Status` could
-        #     be used directly after any stripping needed for security/privacy reasons.
+        # You can find out more about this error model and how to work with it in the
+        # [API Design Guide](https://cloud.google.com/apis/design/errors).
       "message": "A String", # A developer-facing error message, which should be in English. Any
           # user-facing error message should be localized and sent in the
           # google.rpc.Status.details field, or localized by the client.
@@ -463,22 +394,6 @@
         },
       ],
     },
-    "done": True or False, # If the value is `false`, it means the operation is still in progress.
-        # If `true`, the operation is completed, and either `error` or `response` is
-        # available.
-    "response": { # The normal response of the operation in case of success.  If the original
-        # method returns no data on success, such as `Delete`, the response is
-        # `google.protobuf.Empty`.  If the original method is standard
-        # `Get`/`Create`/`Update`, the response should be the resource.  For other
-        # methods, the response should have the type `XxxResponse`, where `Xxx`
-        # is the original method name.  For example, if the original method name
-        # is `TakeSnapshot()`, the inferred response type is
-        # `TakeSnapshotResponse`.
-      "a_key": "", # Properties of the object. Contains field @type with type URL.
-    },
-    "name": "A String", # The server-assigned name, which is only unique within the same service that
-        # originally returns it. If you use the default HTTP mapping, the
-        # `name` should have the format of `operations/some/unique/name`.
   }</pre>
 </div>