[WIP] - Create the documentation for the integration of Simple Form and Bootstrap.

This PR aims to create a guide showing how this application was built, using Simple Form and Bootstrap.
The documentation page looks like this right now:

![screen shot 2014-04-09 at 3 43 28 pm](https://cloud.githubusercontent.com/assets/611891/2659713/4ed4f6b0-c017-11e3-8341-d3a344d2ec93.png)


Tasks:
- [x] Create the basic structure to the documentation page.
- [x] Add the basic documentation for configuring a new Rails app with Simple Form and Bootstrap.
- [ ] Explain step-by-step the creation process for this app, showing how to build forms with Simple Form and Bootstrap.
- [ ] Improve the documentation style.