Add textproc/py-sphinx-autodoc-typehints

Type hints (PEP 484) support for the Sphinx autodoc extension

This extension allows you to use Python 3 annotations for documenting
acceptable argument types and return value types of functions. This allows you
to use type hints in a very natural fashion.

WWW: https://github.com/agronholm/sphinx-autodoc-typehints

PR: 246625
Submitted by: Andreas Bilke <andreas@bilke.org>