Offline-documentation cleanup

This patchset cleans up the offline documentation:

 * Update old references to svn with references to git

 * Remove direct links to online resources - Those do not belong into the
   offline documentation, and are already easily available on the homepage.

 * Remove stub content that only pointed to online location

 * Unify indentation stuff
I think this is, in general, useful information. With the svn hunk below gone (and never correct anyway), the page has little to say, though. Can we move this information elsewhere?