📝Document Enum Members by using #:; Remove 🔥 DocStrEnum approach that turned out to not work

[hf-kklein]

The last approaches to have documented enum members (not only classes) on read the docs resulted in a heuristic trial and error development process (see #75).

Now here's the next step to ultimate documentation truth on how to really do it (aka "richtig statt falsch"):

• instead of adding docstrings somewhen at runtime (🎈 Add Docstrings to Anrede Enum Members #75), add docs at "compile" time instead
• use comments with #: prefix as decribed here Python 3.4 enum classes not working (only py34 environment) sphinx-doc/sphinx#3255
• test the docs locally (instead of waiting for readthedocs to update) by running tox - docs and checking the HTML output in .tox/docs/tmp/html

Works on my machine:

[hf-aschloegl]

Ja, schicke Sache 👍