[Tails-l10n] (review)[de] Release notes 2.12

Hi,
I translated the release notes for 2.12 (and made a minor update wrt.
2.11 release notes).
Please review:

https://gitlab.com/spriver/tails.git
branch: de_tails_212
HEAD commit: a934b67 Fix listing

Affected files:
wiki/src/news/version_2.12.de.po
wiki/src/security/Numerous_security_holes_in_2.10.de.po
wiki/src/security/Numerous_security_holes_in_2.11.de.po

Cheers!
spriver