Release v1.6.0 (#324)

* Update version and changelog for v1.6.0
* Update docs
diff --git a/docs/dyn/runtimeconfig_v1beta1.projects.configs.variables.html b/docs/dyn/runtimeconfig_v1beta1.projects.configs.variables.html
index 003e455..b1837b9 100644
--- a/docs/dyn/runtimeconfig_v1beta1.projects.configs.variables.html
+++ b/docs/dyn/runtimeconfig_v1beta1.projects.configs.variables.html
@@ -90,6 +90,9 @@
   <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="#testIamPermissions">testIamPermissions(resource=None, x__xgafv=None, permissions=None)</a></code></p>
+<p class="firstline">Returns permissions that a caller has on the specified resource.</p>
+<p class="toc_element">
   <code><a href="#update">update(name=None, body, x__xgafv=None)</a></code></p>
 <p class="firstline">Updates an existing variable with a new value.</p>
 <p class="toc_element">
@@ -119,17 +122,16 @@
     # `ports/serving_port` is a valid variable name. The variable value is an
     # opaque string and only leaf variables can have values (that is, variables
     # that do not have any child variables).
-  "text": "A String", # The textual value of the variable. The length of the value must be less
-      # than 4096 bytes. Empty values are also accepted.
-      # NB: Only one of value and string_value can be set at the same time.
+  "text": "A String", # The string value of the variable. The length of the value must be less
+      # than 4096 bytes. Empty values are also accepted. For example,
+      # <code>text: "my text value"</code>.
   "updateTime": "A String", # [Output Only] The time of the last variable update.
   "state": "A String", # [Ouput only] The current state of the variable. The variable state indicates
       # the outcome of the `variables().watch` call and is visible through the
       # `get` and `list` calls.
   "value": "A String", # The binary value of the variable. The length of the value must be less
       # than 4096 bytes. Empty values are also accepted. The value must be
-      # Base64 encoded.
-      # NB: Only one of value and string_value can be set at the same time.
+      # base64 encoded. Only one of `value` or `text` can be set.
   "name": "A String", # The name of the variable resource, in the format:
       # 
       #     projects/[PROJECT_ID]/configs/[CONFIG_NAME]/variables/[VARIABLE_NAME]
@@ -148,13 +150,16 @@
       # Once you create a variable, you cannot change the variable name.
 }
 
-  requestId: string, An optional unique request_id. If server receives two Create requests with
-the same request_id then second request will be ignored and the resource
-stored in the backend will be returned. Empty request_id fields are
-ignored.
-It is responsibility of the client to ensure uniqueness of the request_id
-strings.
-The strings are limited to 64 characters.
+  requestId: string, An optional but recommended unique <code>request_id</code>. If the server
+receives two <code>create()</code> requests  with the same
+<code>request_id</code>, then the second request will be ignored and the
+first resource created and stored in the backend is returned.
+Empty <code>request_id</code> fields are ignored.
+
+It is responsibility of the client to ensure uniqueness of the
+<code>request_id</code> strings.
+
+<code>request_id</code> strings are limited to 64 characters.
   x__xgafv: string, V1 error format.
     Allowed values
       1 - v1 error format
@@ -168,17 +173,16 @@
       # `ports/serving_port` is a valid variable name. The variable value is an
       # opaque string and only leaf variables can have values (that is, variables
       # that do not have any child variables).
-    "text": "A String", # The textual value of the variable. The length of the value must be less
-        # than 4096 bytes. Empty values are also accepted.
-        # NB: Only one of value and string_value can be set at the same time.
+    "text": "A String", # The string value of the variable. The length of the value must be less
+        # than 4096 bytes. Empty values are also accepted. For example,
+        # <code>text: "my text value"</code>.
     "updateTime": "A String", # [Output Only] The time of the last variable update.
     "state": "A String", # [Ouput only] The current state of the variable. The variable state indicates
         # the outcome of the `variables().watch` call and is visible through the
         # `get` and `list` calls.
     "value": "A String", # The binary value of the variable. The length of the value must be less
         # than 4096 bytes. Empty values are also accepted. The value must be
-        # Base64 encoded.
-        # NB: Only one of value and string_value can be set at the same time.
+        # base64 encoded. Only one of `value` or `text` can be set.
     "name": "A String", # The name of the variable resource, in the format:
         #
         #     projects/[PROJECT_ID]/configs/[CONFIG_NAME]/variables/[VARIABLE_NAME]
@@ -254,17 +258,16 @@
       # `ports/serving_port` is a valid variable name. The variable value is an
       # opaque string and only leaf variables can have values (that is, variables
       # that do not have any child variables).
-    "text": "A String", # The textual value of the variable. The length of the value must be less
-        # than 4096 bytes. Empty values are also accepted.
-        # NB: Only one of value and string_value can be set at the same time.
+    "text": "A String", # The string value of the variable. The length of the value must be less
+        # than 4096 bytes. Empty values are also accepted. For example,
+        # <code>text: "my text value"</code>.
     "updateTime": "A String", # [Output Only] The time of the last variable update.
     "state": "A String", # [Ouput only] The current state of the variable. The variable state indicates
         # the outcome of the `variables().watch` call and is visible through the
         # `get` and `list` calls.
     "value": "A String", # The binary value of the variable. The length of the value must be less
         # than 4096 bytes. Empty values are also accepted. The value must be
-        # Base64 encoded.
-        # NB: Only one of value and string_value can be set at the same time.
+        # base64 encoded. Only one of `value` or `text` can be set.
     "name": "A String", # The name of the variable resource, in the format:
         #
         #     projects/[PROJECT_ID]/configs/[CONFIG_NAME]/variables/[VARIABLE_NAME]
@@ -322,17 +325,16 @@
           # `ports/serving_port` is a valid variable name. The variable value is an
           # opaque string and only leaf variables can have values (that is, variables
           # that do not have any child variables).
-        "text": "A String", # The textual value of the variable. The length of the value must be less
-            # than 4096 bytes. Empty values are also accepted.
-            # NB: Only one of value and string_value can be set at the same time.
+        "text": "A String", # The string value of the variable. The length of the value must be less
+            # than 4096 bytes. Empty values are also accepted. For example,
+            # <code>text: "my text value"</code>.
         "updateTime": "A String", # [Output Only] The time of the last variable update.
         "state": "A String", # [Ouput only] The current state of the variable. The variable state indicates
             # the outcome of the `variables().watch` call and is visible through the
             # `get` and `list` calls.
         "value": "A String", # The binary value of the variable. The length of the value must be less
             # than 4096 bytes. Empty values are also accepted. The value must be
-            # Base64 encoded.
-            # NB: Only one of value and string_value can be set at the same time.
+            # base64 encoded. Only one of `value` or `text` can be set.
         "name": "A String", # The name of the variable resource, in the format:
             #
             #     projects/[PROJECT_ID]/configs/[CONFIG_NAME]/variables/[VARIABLE_NAME]
@@ -369,6 +371,36 @@
 </div>
 
 <div class="method">
+    <code class="details" id="testIamPermissions">testIamPermissions(resource=None, x__xgafv=None, permissions=None)</code>
+  <pre>Returns permissions that a caller has on the specified resource.
+If the resource does not exist, this will return an empty set of
+permissions, not a NOT_FOUND error.
+
+Args:
+  resource: string, REQUIRED: The resource for which the policy detail is being requested.
+`resource` is usually specified as a path. For example, a Project
+resource is specified as `projects/{project}`. (required)
+  x__xgafv: string, V1 error format.
+    Allowed values
+      1 - v1 error format
+      2 - v2 error format
+  permissions: string, The set of permissions to check for the `resource`. Permissions with
+wildcards (such as '*' or 'storage.*') are not allowed. For more
+information see
+[IAM Overview](https://cloud.google.com/iam/docs/overview#permissions). (repeated)
+
+Returns:
+  An object of the form:
+
+    { # Response message for `TestIamPermissions` method.
+    "permissions": [ # A subset of `TestPermissionsRequest.permissions` that the caller is
+        # allowed.
+      "A String",
+    ],
+  }</pre>
+</div>
+
+<div class="method">
     <code class="details" id="update">update(name=None, body, x__xgafv=None)</code>
   <pre>Updates an existing variable with a new value.
 
@@ -384,17 +416,16 @@
     # `ports/serving_port` is a valid variable name. The variable value is an
     # opaque string and only leaf variables can have values (that is, variables
     # that do not have any child variables).
-  "text": "A String", # The textual value of the variable. The length of the value must be less
-      # than 4096 bytes. Empty values are also accepted.
-      # NB: Only one of value and string_value can be set at the same time.
+  "text": "A String", # The string value of the variable. The length of the value must be less
+      # than 4096 bytes. Empty values are also accepted. For example,
+      # <code>text: "my text value"</code>.
   "updateTime": "A String", # [Output Only] The time of the last variable update.
   "state": "A String", # [Ouput only] The current state of the variable. The variable state indicates
       # the outcome of the `variables().watch` call and is visible through the
       # `get` and `list` calls.
   "value": "A String", # The binary value of the variable. The length of the value must be less
       # than 4096 bytes. Empty values are also accepted. The value must be
-      # Base64 encoded.
-      # NB: Only one of value and string_value can be set at the same time.
+      # base64 encoded. Only one of `value` or `text` can be set.
   "name": "A String", # The name of the variable resource, in the format:
       # 
       #     projects/[PROJECT_ID]/configs/[CONFIG_NAME]/variables/[VARIABLE_NAME]
@@ -426,17 +457,16 @@
       # `ports/serving_port` is a valid variable name. The variable value is an
       # opaque string and only leaf variables can have values (that is, variables
       # that do not have any child variables).
-    "text": "A String", # The textual value of the variable. The length of the value must be less
-        # than 4096 bytes. Empty values are also accepted.
-        # NB: Only one of value and string_value can be set at the same time.
+    "text": "A String", # The string value of the variable. The length of the value must be less
+        # than 4096 bytes. Empty values are also accepted. For example,
+        # <code>text: "my text value"</code>.
     "updateTime": "A String", # [Output Only] The time of the last variable update.
     "state": "A String", # [Ouput only] The current state of the variable. The variable state indicates
         # the outcome of the `variables().watch` call and is visible through the
         # `get` and `list` calls.
     "value": "A String", # The binary value of the variable. The length of the value must be less
         # than 4096 bytes. Empty values are also accepted. The value must be
-        # Base64 encoded.
-        # NB: Only one of value and string_value can be set at the same time.
+        # base64 encoded. Only one of `value` or `text` can be set.
     "name": "A String", # The name of the variable resource, in the format:
         #
         #     projects/[PROJECT_ID]/configs/[CONFIG_NAME]/variables/[VARIABLE_NAME]
@@ -501,17 +531,16 @@
       # `ports/serving_port` is a valid variable name. The variable value is an
       # opaque string and only leaf variables can have values (that is, variables
       # that do not have any child variables).
-    "text": "A String", # The textual value of the variable. The length of the value must be less
-        # than 4096 bytes. Empty values are also accepted.
-        # NB: Only one of value and string_value can be set at the same time.
+    "text": "A String", # The string value of the variable. The length of the value must be less
+        # than 4096 bytes. Empty values are also accepted. For example,
+        # <code>text: "my text value"</code>.
     "updateTime": "A String", # [Output Only] The time of the last variable update.
     "state": "A String", # [Ouput only] The current state of the variable. The variable state indicates
         # the outcome of the `variables().watch` call and is visible through the
         # `get` and `list` calls.
     "value": "A String", # The binary value of the variable. The length of the value must be less
         # than 4096 bytes. Empty values are also accepted. The value must be
-        # Base64 encoded.
-        # NB: Only one of value and string_value can be set at the same time.
+        # base64 encoded. Only one of `value` or `text` can be set.
     "name": "A String", # The name of the variable resource, in the format:
         #
         #     projects/[PROJECT_ID]/configs/[CONFIG_NAME]/variables/[VARIABLE_NAME]