Set up `mkdocs` for a team documentation page.

[zkbt]

Let's try to write some living documentation for our research team. It should help make it easier for new folks joining the team, give a clearer sense of expectations of everyone, and try to make visible ideas and assumptions and goals that are often unspoken.

To practice some of our other tools while doing this, let's just use code documentation tools to render simple files into a nice webpage. Lately I've liked mkdocs, but I could be easily convinced to switch to sphinx if folks tell me its better. For this task, we should just set up a basic documentation page.

[zkbt]

(Other issues with describe sections to include.)

[zkbt]

It mostly exists, but it might benefit from a brief pleasant moment of picking a nicer theme color.