Enum values docstrings

[dyollb]

fix merge conflicts from #225

Close #225

[ax3l]

@gentlegiantJGC do you like to help with the review of this one?

[gentlegiantJGC]

Something is wrong with the tests. I can't tell if the code is not working or if the tests are wrong.

This bit just looks like the docstring in the tests are wrong.

-      Green
+      Green : Green color

I don't understand this diff. Which is the ground truth and which is the generated? It doesn't seem to match the test files.
It is adding docstrings to the exported module level variables. Is this correct?

 Blue: ConsoleForegroundColor  # value = <ConsoleForegroundColor.Blue: 34>
+"""
+Blue color
+"""

We should also add tests for py::native_enum which I assume behaves a little different to the old enum.