Update README.md

Add Compilebytes PHP compiler to Web Applications section

README.md

 * [PHP Queue](https://github.com/CoderKungfu/php-queue) - An application for managing queueing backends.
 * [phpRedisAdmin](https://github.com/ErikDubbelboer/phpRedisAdmin) - A simple web interface to manage [Redis](https://redis.io/) databases.
 * [PHPSandbox](https://phpsandbox.io) - An online IDE for PHP in the browser.
+* [CompileBytes PHP Compiler](https://www.compilebytes.com/tools/php) - Online PHP compiler and code execution sandbox.
 
 ### Infrastructure
 *Infrastructure for providing PHP applications and services.*