Improves the documentation 💅

Author: pirelenito

README.md

@@ -4,11 +4,13 @@ Simple [webpack](http://webpack.github.io/) plugin that generates `VERSION` and
 
 ## Usage
 
+Given a webpack project, install it as a local development dependency:
+
 ```bash
 npm install --save-dev git-revision-webpack-plugin
 ```
 
-Sample webpack config:
+Then, simply configure it as a plugin in the webpack config:
 
 ```javascript
 var GitRevisionPlugin = require('git-revision-webpack-plugin')
@@ -19,3 +21,15 @@ module.exports = {
   ]
 }
 ```
+
+It outputs a `VERSION` based on [git-describe](http://www.git-scm.com/docs/git-describe) such as:
+
+```
+v0.0.0-34-g7c16d8b
+```
+
+And a `COMMITHASH` such as:
+
+```
+7c16d8b1abeced419c14eb9908baeb4229ac0542
+```