Docs reformatting

Author: kamermans

README.md

@@ -1,18 +1,15 @@
-=======================
-Guzzle OAuth 2.0 Subscriber
-=======================
+# Guzzle OAuth 2.0 Subscriber
 
 This is an OAuth 2.0 client for Guzzle which aims to be 100% compatible with Guzzle 4, 5, 6 and all future versions within a single package.
 Although I love Guzzle, its interfaces keep changing, causing massive breaking changes every 12 months or so, so I have created this package
 to help reduce the dependency hell that most third-party Guzzle dependencies bring with them.  I wrote the official Guzzle OAuth 2.0 plugin
 which is still on the `oauth2` branch, [over at the official Guzzle repo](https://github.com/guzzle/oauth-subscriber/tree/oauth2), but I
 see that they have dropped support for Guzzle < v6 on `master`, which prompted me to split this back off to a separate package.
 
-Installing
-==========
+## Installing
 
 This project can be installed using Composer. Add the following to your
-composer.json:
+`composer.json`:
 
 ```javascript
     {