Docs to describe updating the docs

[lisroach]

I found myself unsure of how to update the docs other than regenerating them with tox -e docs

We should update the README to explain the steps:

1. activate the venv
2. Run jupyter notebook
3. This will launch a browser window where you can edit the docs directly
4. Use "save and checkpoint" -> I think?
5. Regenerate the docs with tox -e docs

[srisatya12]

@lisroach will try to work on this.

[Jackenmen]

I suggest also mentioning that one should use "Cell -> All Output -> Clear" option before committing (or setting up a pre save hook):

[amyreese]

We are dropping the notebook-based docs.