[Tails-l10n] (review)[de] wiki/src/doc.de.po

Hi,
I translated most of the pages regarding the 2.4 release, based upon
"testing" branch.
This one is not that much work:

https://gitlab.com/spriver/tails.git
Branch: de_doc
HEAD commit: f3996ce Translated new translated strings
Affected files:
config/base_branch
wiki/src/doc.de.po

Cheers!
spriver