fix(servicemanagement): update the API

#### servicemanagement:v1

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

discovery/servicemanagement-v1.json

@@ -829,7 +829,7 @@
       }
     }
   },
-  "revision": "20210409",
+  "revision": "20210416",
   "rootUrl": "https://servicemanagement.googleapis.com/",
   "schemas": {
     "Advice": {
@@ -993,7 +993,7 @@
       "type": "object"
     },
     "Authentication": {
-      "description": "`Authentication` defines the authentication configuration for an API. Example for an API targeted for external use: name: calendar.googleapis.com authentication: providers: - id: google_calendar_auth jwks_uri: https://www.googleapis.com/oauth2/v1/certs issuer: https://securetoken.google.com rules: - selector: \"*\" requirements: provider_id: google_calendar_auth",
+      "description": "`Authentication` defines the authentication configuration for API methods provided by an API service. Example: name: calendar.googleapis.com authentication: providers: - id: google_calendar_auth jwks_uri: https://www.googleapis.com/oauth2/v1/certs issuer: https://securetoken.google.com rules: - selector: \"*\" requirements: provider_id: google_calendar_auth - selector: google.calendar.Delegate oauth: canonical_scopes: https://www.googleapis.com/auth/calendar.read",
       "id": "Authentication",
       "properties": {
         "providers": {

src/apis/servicemanagement/v1.ts

@@ -196,7 +196,7 @@ export namespace servicemanagement_v1 {
     logType?: string | null;
   }
   /**
-   * `Authentication` defines the authentication configuration for an API. Example for an API targeted for external use: name: calendar.googleapis.com authentication: providers: - id: google_calendar_auth jwks_uri: https://www.googleapis.com/oauth2/v1/certs issuer: https://securetoken.google.com rules: - selector: "*" requirements: provider_id: google_calendar_auth
+   * `Authentication` defines the authentication configuration for API methods provided by an API service. Example: name: calendar.googleapis.com authentication: providers: - id: google_calendar_auth jwks_uri: https://www.googleapis.com/oauth2/v1/certs issuer: https://securetoken.google.com rules: - selector: "*" requirements: provider_id: google_calendar_auth - selector: google.calendar.Delegate oauth: canonical_scopes: https://www.googleapis.com/auth/calendar.read
    */
   export interface Schema$Authentication {
     /**