[Tails-l10n] (review)[de] Various tiny changes

Hi,
I translated and unfuzzied some small fuzzy and new strings on several
pages. This delta is really small (;

Please review:

https://gitlab.com/spriver/tails.git
branch: de_various
HEAD commit: e42b688 Unfuzzied strings

Affected files:
wiki/src/doc/about/fingerprint.de.po
wiki/src/doc/about/openpgp_keys.de.po
wiki/src/doc/first_steps/startup_options/administration_password.de.po


Cheers!
spriver