Rules are missing docs

Can we add docs for these rules? Ideally ones that follow the template suggested by ESLint's internal rules? Could be split into per-rule PRs.

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We have an internal version of docs for must-colocate-fragment which I'd dropped here. Someone could use that as a starting place for OSS docs: https://gist.github.com/captbaritone/42c183b03df984e0db4dcfd0fc24bfdf
