Split system and administrative docs

Hi @matias78 and @AlphaGit, I have moved some documents, anyway, there is still work to do as you can see in Trello: [Manual de sistema](https://trello.com/c/DuRWcUQe/105-manual-de-sistema) and [Manual de administrador](https://trello.com/c/OM0a4Iyp/106-manual-de-administrador).

I am not sure why there are `index.markdown` files in anywhere, but I updated topic rendering to ignore them.

The main idea is to use `Manual de Usuario` section for any user oriented functionality, including configuration. `Manual de Implantacion y Mantenimiento` (we can review the name) for installation and advanced or low level configuration (outside of our system), `Manual de Sistema` to describe how the system works, and `Proyecto` for workflow definitions and retrospectives about our decisions.