[Tails-dev] (review) doc: minor fixes and git documentation

Hi,

please review and merge the following commits in matsa/master:

* 7f7fccc - progit is available in several languages
* 5c6b805 - doc: add pointers to git basics
* 399bd0a - adding SubraphOs to similar projects
* a2cb29d - formating
* 9c6b138 - Merge branch 'master', remote branch 'origin'
* a6ae773 - l10n-tricks : disable languages at build time
* a00d2dc - [fr] fix link

Thanks, and cheers