Hi,
here's a translation for the warning page shown in the Unsafe Browser
when it initially starts.
(The work is based on the testing branch, please tell me if that's wrong.)
Please review:
https://gitlab.com/flapflap/tails
branch: de-unsafe-browser-warning
HEAD commit: c364ce3e - [de] initial translation
Comments:
- The term "captive portal" was left untranslated because I don't know
  of a commonly understandable translation.  Also, Wikipedia uses
  "Captive Portal": 
https://de.wikipedia.org/wiki/Captive_Portal
- The page mentions "businesses" as an example where captive portals
  are used.  Does this really refer to generic businesses, or does it
  refer to "stores", for example, as they are common in padestrian
  zones in the city centre?
  The translation currently uses the latter interpretation
  ("Geschäfte"), in case the former is meant, this needs to be fixed.
Cheers,
~flapflap