Bug#578730: [i18n:de] German translation for debian specific changes to gdm3

[Gert Michael Kulyk]

> Thanks for the translation.

Nothing to thank for, I thank you for pushing it into the package.

> BTW there is a second file for the Debian-specific desktop file. Could
> you also translate it?

Do you mean the file you've already comitted? At least the changelog for
2.30.0-2 mentions my name :-)

Greetings,

Gert