docs: docs update (#911)

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Fixes #<issue_number_goes_here> 🦕
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+<h1><a href="spanner_v1.html">Cloud Spanner API</a> . <a href="spanner_v1.projects.html">projects</a> . <a href="spanner_v1.projects.instances.html">instances</a> . <a href="spanner_v1.projects.instances.databaseOperations.html">databaseOperations</a></h1>
+<h2>Instance Methods</h2>
+<p class="toc_element">
+  <code><a href="#list">list(parent, filter=None, pageToken=None, pageSize=None, x__xgafv=None)</a></code></p>
+<p class="firstline">Lists database longrunning-operations.</p>
+<p class="toc_element">
+  <code><a href="#list_next">list_next(previous_request, previous_response)</a></code></p>
+<p class="firstline">Retrieves the next page of results.</p>
+<h3>Method Details</h3>
+<div class="method">
+    <code class="details" id="list">list(parent, filter=None, pageToken=None, pageSize=None, x__xgafv=None)</code>
+  <pre>Lists database longrunning-operations.
+A database operation has a name of the form
+`projects/&lt;project&gt;/instances/&lt;instance&gt;/databases/&lt;database&gt;/operations/&lt;operation&gt;`.
+The long-running operation
+metadata field type
+`metadata.type_url` describes the type of the metadata. Operations returned
+include those that have completed/failed/canceled within the last 7 days,
+and pending operations.
+
+Args:
+  parent: string, Required. The instance of the database operations.
+Values are of the form `projects/&lt;project&gt;/instances/&lt;instance&gt;`. (required)
+  filter: string, An expression that filters the list of returned operations.
+
+A filter expression consists of a field name, a
+comparison operator, and a value for filtering.
+The value must be a string, a number, or a boolean. The comparison operator
+must be one of: `&lt;`, `&gt;`, `&lt;=`, `&gt;=`, `!=`, `=`, or `:`.
+Colon `:` is the contains operator. Filter rules are not case sensitive.
+
+The following fields in the Operation
+are eligible for filtering:
+
+  * `name` - The name of the long-running operation
+  * `done` - False if the operation is in progress, else true.
+  * `metadata.@type` - the type of metadata. For example, the type string
+     for RestoreDatabaseMetadata is
+     `type.googleapis.com/google.spanner.admin.database.v1.RestoreDatabaseMetadata`.
+  * `metadata.&lt;field_name&gt;` - any field in metadata.value.
+  * `error` - Error associated with the long-running operation.
+  * `response.@type` - the type of response.
+  * `response.&lt;field_name&gt;` - any field in response.value.
+
+You can combine multiple expressions by enclosing each expression in
+parentheses. By default, expressions are combined with AND logic. However,
+you can specify AND, OR, and NOT logic explicitly.
+
+Here are a few examples:
+
+  * `done:true` - The operation is complete.
+  * `(metadata.@type=type.googleapis.com/google.spanner.admin.database.v1.RestoreDatabaseMetadata) AND` &lt;br/&gt;
+    `(metadata.source_type:BACKUP) AND` &lt;br/&gt;
+    `(metadata.backup_info.backup:backup_howl) AND` &lt;br/&gt;
+    `(metadata.name:restored_howl) AND` &lt;br/&gt;
+    `(metadata.progress.start_time &lt; \&quot;2018-03-28T14:50:00Z\&quot;) AND` &lt;br/&gt;
+    `(error:*)` - Return operations where:
+    * The operation&#x27;s metadata type is RestoreDatabaseMetadata.
+    * The database is restored from a backup.
+    * The backup name contains &quot;backup_howl&quot;.
+    * The restored database&#x27;s name contains &quot;restored_howl&quot;.
+    * The operation started before 2018-03-28T14:50:00Z.
+    * The operation resulted in an error.
+  pageToken: string, If non-empty, `page_token` should contain a
+next_page_token
+from a previous ListDatabaseOperationsResponse to the
+same `parent` and with the same `filter`.
+  pageSize: integer, Number of operations to be returned in the response. If 0 or
+less, defaults to the server&#x27;s maximum allowed page size.
+  x__xgafv: string, V1 error format.
+    Allowed values
+      1 - v1 error format
+      2 - v2 error format
+
+Returns:
+  An object of the form:
+
+    { # The response for
+      # ListDatabaseOperations.
+    &quot;nextPageToken&quot;: &quot;A String&quot;, # `next_page_token` can be sent in a subsequent
+        # ListDatabaseOperations
+        # call to fetch more of the matching metadata.
+    &quot;operations&quot;: [ # The list of matching database long-running
+        # operations. Each operation&#x27;s name will be
+        # prefixed by the database&#x27;s name. The operation&#x27;s
+        # metadata field type
+        # `metadata.type_url` describes the type of the metadata.
+      { # This resource represents a long-running operation that is the result of a
+          # network API call.
+        &quot;done&quot;: 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.
+        &quot;response&quot;: { # 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`.
+          &quot;a_key&quot;: &quot;&quot;, # Properties of the object. Contains field @type with type URL.
+        },
+        &quot;name&quot;: &quot;A String&quot;, # 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}`.
+        &quot;error&quot;: { # 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). Each `Status` message contains
+            # three pieces of data: error code, error message, and error details.
+            #
+            # 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).
+          &quot;code&quot;: 42, # The status code, which should be an enum value of google.rpc.Code.
+          &quot;message&quot;: &quot;A String&quot;, # 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.
+          &quot;details&quot;: [ # A list of messages that carry the error details.  There is a common set of
+              # message types for APIs to use.
+            {
+              &quot;a_key&quot;: &quot;&quot;, # Properties of the object. Contains field @type with type URL.
+            },
+          ],
+        },
+        &quot;metadata&quot;: { # 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.
+          &quot;a_key&quot;: &quot;&quot;, # Properties of the object. Contains field @type with type URL.
+        },
+      },
+    ],
+  }</pre>
+</div>
+
+<div class="method">
+    <code class="details" id="list_next">list_next(previous_request, previous_response)</code>
+  <pre>Retrieves the next page of results.
+
+Args:
+  previous_request: The request for the previous page. (required)
+  previous_response: The response from the request for the previous page. (required)
+
+Returns:
+  A request object that you can call &#x27;execute()&#x27; on to request the next
+  page. Returns None if there are no more items in the collection.
+    </pre>
+</div>
+
+</body></html>
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