Add tutorial: Build Your Own Git With PHP

Author: Omar-Ahmed-Elshiekh

README.md

@@ -229,6 +229,7 @@ It's a great way to learn.
 * [**Python**: _Write yourself a Git!_](https://wyag.thb.lt/)
 * [**Python**: _ugit: Learn Git Internals by Building Git Yourself_](https://www.leshenko.net/p/ugit/)
 * [**Ruby**: _Rebuilding Git in Ruby_](https://robots.thoughtbot.com/rebuilding-git-in-ruby)
+* [**PHP**: _Build & Learn Git with PHP_](https://omar-ahmed-elshiekh.github.io/git-php-doc-website/)
 
 #### Build your own `Network Stack`