Mark DE translation as inactive

Hi all,

the German translation of the PHP manual isn't quite up to date for some
time now[1].  Even worse, the build is broken for six weeks now, so even
updates to untranslated pages (and rendering changes regarding PhD) are
rolled out, and apparently nobody is working on that.

So, unless someone is planning to work on that soon, I suggest to mark
the DE translation as inactive for the time being; see
<https://github.com/php/web-php/pull/430>.

Having no translation is better than having a bad translation. ;)

[1] <http://doc.php.net/revcheck.php?p=3Dgraph&lang=3Dde>

=2D-
Christoph M. Becker