Update docs styling

Not a massive change, just something that makes the docs easier to read and navigate.

@nickjs @pushrax @BlakeMesdag 

### Before
![screen shot 2013-10-08 at 9 58 30 am](https://f.cloud.github.com/assets/370323/1289498/54f5e174-3022-11e3-9eb8-a5a2b7de5537.png)

### After
![screen shot 2013-10-08 at 10 00 56 am](https://f.cloud.github.com/assets/370323/1289499/592f48d4-3022-11e3-9ce0-8f761134c000.png)