Update Contributing Docs (#1915)

* Update Contributing Docs
- Update docs with all new tox hotness
- Test running docs build:
  - `sphinx-build -a -b html -W docs/ docs/_build/`

Fixes #1907

* Fix docs/contributing_to_black.md lint

* Remove autogenerated copy pasta

* Fix review typos + regen automated docs via Running Sphinx v1.8.5