[WIP] Fix a lot of Sphinx stuff in the getting started articles

This PR contains a lot of minor fixes, so let me explain what's included:

 - Fixing incorrect formats (some lists were not correctly)
 - Fixing inconsistencies
 - Make sure the document follows the Symfony standards
 - Break some lines after he 72th character.
 - Add some missing formats

This PR don't change all lines to wrap after the 72th character, because that will mean unreadable diffs. Someone need to do that in a seperate PR.