fix: fix documentation build and docs

[tk-woven]

Description

In an attempt to address a CVE (CVE-2022-34749) for one of our docs dependencies, mistune, I found multiple issues. The first is that we cannot address the CVE until some Sphinx API issues are solved in upstream Sphinx. The second issue is that our docs building is broken, presumably by the update to Python 3.7 as some regexs from rinohtype were failing to compile. This work fixes the docs build and also updates the documentation for completeness.

m2r2, which requires mistune, was having us install the newer version of mistune that breaks against the Sphinx API, so we have to update m2r2 to use a version that pins against the older mistune.

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This change is 

[wadimkehl]

Reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @chrisochoatri and @kuanleetri)