Change headings for Contributing and TOC sections.

README.md

 # Awesome PHP
 A curated list of amazingly awesome PHP libraries, resources and shiny things.
 
-# Contributing
+## Contributing
 Please see [CONTRIBUTING](https://github.com/ziadoz/awesome-php/blob/master/CONTRIBUTING.md) for details.
 
-# Table of Contents
+## Table of Contents
 - [Awesome PHP](#awesome-php)
 	- [Dependency Management](#dependency-management)
 	- [Dependency Management Extras](#dependency-management-extras)