Switch documentation from `ReadTheDocs` to `mkdocs-material`

[Archmonger]

Current Situation

I personally dislike rst documentation quite a bit. In my opinion, it's very convoluted and is difficult to read/maintain.

Proposed Actions

We should migrate the docs to use mkdocs-material when we get a chance.

System Information

No response

[johnthagen]

I support this for all the same reasons.

[Archmonger]

Since this ticket has very low complexity, going to use this to test whether the new "GitHub AI Agent" feature can automagically complete this.

[Archmonger]

It overall did pretty well.

The copilot agent only made one significant mistake - it accidentally committed the compiled docs to the PR branch.

All other "manually interventions" on that PR were purely to shoehorn in some grammatical or stylistic changes.