fix: extracted docs page for Cloud Run (#1768)

Author: justinmahood

run/helloworld/index.php

@@ -1,4 +1,4 @@
-<?php
+<!--
 /**
  * Copyright 2020 Google LLC.
  *
@@ -17,6 +17,8 @@
 
 // [START cloudrun_helloworld_service]
 // [START run_helloworld_service]
+-->
+<?php
 
 $name = getenv('NAME', true) ?: 'World';
 echo sprintf('Hello %s!', $name);