[Tails-l10n] (review)[de] 2.11 release notes

Hi,
(please note that the release notes for 2.10 have not been reviewed yet:
https://mailman.boum.org/pipermail/tails-l10n/2017-February/004507.html)

I translated the release notes for Tails 2.11.
Please review:

https://gitlab.com/spriver/tails.git
branch: de_tails_211
HEAD commit: 91be34f Grammar

Affected files:
wiki/src/news/version_2.11.de.po
wiki/src/security/Numerous_security_holes_in_2.10.de.po

Cheers!
spriver