chore(compute): Migrate region tag (GoogleCloudPlatform#4047)

* chore(compute): Migrate region tag

* chore(compute): Rename region tag

Author: rudrakhsha-crest

compute/sendgrid.js

@@ -14,6 +14,7 @@
 
 'use strict';
 
+// [START compute_sendgrid]
 // [START compute_send]
 // This sample is based off of:
 // https://github.com/sendgrid/sendgrid-nodejs/tree/master/packages/mail
@@ -30,3 +31,4 @@ async function sendgridExample() {
 }
 sendgridExample();
 // [END compute_send]
+// [END compute_sendgrid]