feat(apigateway): update the API

#### apigateway:v1beta
The following keys were added:
- schemas.ApigatewayBinding.properties.bindingId.type

The following keys were changed:
- schemas.ApigatewayApiConfig.description

discovery/apigateway-v1beta.json

@@ -1083,7 +1083,7 @@
       }
     }
   },
-  "revision": "20201022",
+  "revision": "20201029",
   "rootUrl": "https://apigateway.googleapis.com/",
   "schemas": {
     "ApigatewayApi": {
@@ -1147,7 +1147,7 @@
       "type": "object"
     },
     "ApigatewayApiConfig": {
-      "description": "An API Configuration is an association of an API Controller Config and a Gateway Config. For APIs with a Managed Service API Controller, this resource is associated with one or more Service Configs and a Service Rollout. Initially, this resource will extract the Gateway Config from the API Controller Config.",
+      "description": "An API Configuration is a combination of settings for both the Managed Service and Gateways serving this API Config.",
       "id": "ApigatewayApiConfig",
       "properties": {
         "createTime": {
@@ -1342,6 +1342,9 @@
       "description": "Associates `members` with a `role`.",
       "id": "ApigatewayBinding",
       "properties": {
+        "bindingId": {
+          "type": "string"
+        },
         "condition": {
           "$ref": "ApigatewayExpr",
           "description": "The condition that is associated with this binding. If the condition evaluates to `true`, then this binding applies to the current request. If the condition evaluates to `false`, then this binding does not apply to the current request. However, a different role binding might grant the same role to one or more of the members in this binding. To learn which resources support conditions in their IAM policies, see the [IAM documentation](https://cloud.google.com/iam/help/conditions/resource-policies)."

src/apis/apigateway/v1beta.ts

@@ -157,7 +157,7 @@ export namespace apigateway_v1beta {
     updateTime?: string | null;
   }
   /**
-   * An API Configuration is an association of an API Controller Config and a Gateway Config. For APIs with a Managed Service API Controller, this resource is associated with one or more Service Configs and a Service Rollout. Initially, this resource will extract the Gateway Config from the API Controller Config.
+   * An API Configuration is a combination of settings for both the Managed Service and Gateways serving this API Config.
    */
   export interface Schema$ApigatewayApiConfig {
     /**
@@ -279,6 +279,7 @@ export namespace apigateway_v1beta {
    * Associates `members` with a `role`.
    */
   export interface Schema$ApigatewayBinding {
+    bindingId?: string | null;
     /**
      * The condition that is associated with this binding. If the condition evaluates to `true`, then this binding applies to the current request. If the condition evaluates to `false`, then this binding does not apply to the current request. However, a different role binding might grant the same role to one or more of the members in this binding. To learn which resources support conditions in their IAM policies, see the [IAM documentation](https://cloud.google.com/iam/help/conditions/resource-policies).
      */