Additional docs for troubleshooting precommit

[sjspielman]

I think I have encountered this before, and it had something to do with the pre-commit cache. First check that you have the latest version of the hook with pre-commit autoupdate -c {your.local.precommit.yml}, but if that does not work you may want to run pre-commit clean and see if that fixes things.

Originally posted by @jashapiro in #642 (comment)

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I'm opening this issue to track a potential "nice to have" doc (either in the precommit page or FAQ) about troubleshooting advanced usage of pre-commit. This approach worked for me, so it may help others if it turns out they encounter it! We can add these docs if we get multiple questions about it.