Define wiki main topics and initial structure

[teles]

At this point of project development would be nice to have a wiki with some information for FrontPress users. I've started a wiki including a installation guide, but I guess would be nice to have more information.

This issue aims to define some initial pages to be included in wiki and its structure. Afterwards the docs repository will be updated with this wiki content.

Readme provides some information to be included in wiki.

@alisonmonteiro @IuryAlves @taciogt @luizotcarvalho @dineshtrivedi do you have any suggestions about wiki topics?