[Doco] Add sub section titles

Author: nulltoken

README.md

@@ -18,6 +18,8 @@ The purpose of this package is to provide an easily configurable OAuth 2 server,
 
 ## How to use
 
+### Installation
+
 Add it to your Node.js project as a development dependency:
 
 With yarn...
@@ -30,6 +32,8 @@ yarn add -D oauth2-mock-server
 npm install --save-dev oauth2-mock-server
 ```
 
+### Quickstart
+
 Here is an example for creating and running a server instance with a single random RSA key:
 
 ```js
@@ -84,6 +88,8 @@ request.get(
 );
 ```
 
+### Customization hooks
+
 It also provides a convenient way, through event emitters, to programmatically customize:
 
 - The JWT access token