Automate the generation of docs/drivers.rst

[lesamouraipourpre]

While investigating #342, a thought struck me:

Would it be possible to automate the generation of docs/drivers.rst when generating circuitpython_library_list.md

A possible source of information would be the keywords passed into setup() in setup.py on the libraries that are uploaded to PyPI. On boards without a setup.py, a keywords.txt could be created. This could also possibly be made feature searchable like the boards matrix has recently.

Thoughts?