Add German translation of parameter type inference

See 722d159.

(There’s one difference to the English original: I clarified “and let
[the parameter types] be inferred” by adding what in English would be
“by the compiler”, since I think the German translation of “inferred” is
a bit less clear.)
Merge pull request #7 from lucaswerkmeister/germanTypeInference

Add German translation of parameter type inference