Update CONTRIBUTING.rst

[neuged]

Is your feature request related to a problem? Please describe.

Currently CONTRIBUTING.rst instructs me to run python setup.py to build and test, but there is no setup.py

Describe the solution you'd like

I would like command line examples on how to build/test/lint the project and the documentation locally.

Describe alternatives you've considered

I have looked at setup.cfg and pyproject.toml. I see that the build tool is flit. I can make up a venv and run flit install --deps all, but then pytest still fails with No module named 'selenium'. I can sort of get a sphinx build of the documentation running with sphinx-build -b html docs /tmp/test but that doesn't pull in the code commentary correctly.

[codingjoe]

Thanks for alerting me about this. I rewrote this bit, to reflect the modern packaging setup.