feat(privateca): update the API

#### privateca:v1beta1
The following keys were added:
- schemas.Binding.properties.bindingId.type

The following keys were changed:
- description

discovery/privateca-v1beta1.json

@@ -12,7 +12,7 @@
   "baseUrl": "https://privateca.googleapis.com/",
   "batchPath": "batch",
   "canonicalName": "Certificate Authority Service",
-  "description": "",
+  "description": "The Certificate Authority Service API is a highly-available, scalable service that enables you to simplify and automate the management of private certificate authorities (CAs) while staying in control of your private keys.\" ",
   "discoveryVersion": "v1",
   "documentationLink": "https://cloud.google.com/",
   "fullyEncodeReservedExpansion": true,
@@ -1292,7 +1292,7 @@
       }
     }
   },
-  "revision": "20201022",
+  "revision": "20201102",
   "rootUrl": "https://privateca.googleapis.com/",
   "schemas": {
     "AccessUrls": {
@@ -1437,6 +1437,9 @@
       "description": "Associates `members` with a `role`.",
       "id": "Binding",
       "properties": {
+        "bindingId": {
+          "type": "string"
+        },
         "condition": {
           "$ref": "Expr",
           "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/privateca/v1beta1.ts

@@ -101,7 +101,7 @@ export namespace privateca_v1beta1 {
   /**
    * Certificate Authority API
    *
-   *
+   * The Certificate Authority Service API is a highly-available, scalable service that enables you to simplify and automate the management of private certificate authorities (CAs) while staying in control of your private keys."
    *
    * @example
    * ```js
@@ -218,6 +218,7 @@ export namespace privateca_v1beta1 {
    * Associates `members` with a `role`.
    */
   export interface Schema$Binding {
+    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).
      */