fix(functions): clarify auth comments (#1427)

* fix: clarify auth comments

* Fix lint

Co-authored-by: Benjamin E. Coe <bencoe@google.com>
Co-authored-by: Daniel Bankhead <danielbankhead@google.com>

samples/idtokens-serverless.js

@@ -33,16 +33,30 @@ function main(
   /**
    * TODO(developer): Uncomment these variables before running the sample.
    */
+  // [END functions_bearer_token]
+  // [END cloudrun_service_to_service_auth]
+
+  // [START cloudrun_service_to_service_auth]
   // Example: https://my-cloud-run-service.run.app/books/delete/12345
   // const url = 'https://TARGET_HOSTNAME/TARGET_URL';
 
-  // [END functions_bearer_token]
   // Example (Cloud Run): https://my-cloud-run-service.run.app/
-  // [START functions_bearer_token]
+  // const targetAudience = 'https://TARGET_AUDIENCE/';
   // [END cloudrun_service_to_service_auth]
+
+  // [START functions_bearer_token]
+  // For Cloud Functions, `endpoint` and `audience` should be equal.
+
+  // Example: https://project-region-projectid.cloudfunctions.net/myFunction
+  // const url = 'https://TARGET_HOSTNAME/TARGET_URL';
+
   // Example (Cloud Functions): https://project-region-projectid.cloudfunctions.net/myFunction
-  // [START cloudrun_service_to_service_auth]
   // const targetAudience = 'https://TARGET_AUDIENCE/';
+  // [END functions_bearer_token]
+
+  // [START functions_bearer_token]
+  // [START cloudrun_service_to_service_auth]
+
   const {GoogleAuth} = require('google-auth-library');
   const auth = new GoogleAuth();