Rename documentation section

Since this section points directly and only to the download page, let's
call it in a similar way.
Remove ampersand

Wikipedia recommends to only use ampersand where space is limited:

https://en.wikipedia.org/wiki/Wikipedia:Manual_of_Style#Ampersand
Merge remote-tracking branch 'origin/doc/wheezy' into testing
Fix files ownership while copying persistence (Closes: #7216)

The previous instructions to copy the persistent data were creating personal
files that belong to root. I don't think there is a way of preserving the
original ownership using Nautilus (unless doing a "move" instead of a "copy" but
that's not what we are trying to do here).
Closing Nautilus is not enough to get back to the prompt
Merge remote-tracking branch 'origin/doc/7216-persistence-backup-permissions' into testing