Docs: Mention jsdoc/no-undefined-types & similar in no-unused-vars docs page

[JoshuaKGoldberg]

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• I have looked for existing open or closed documentation requests that match my proposal.
• I have read the FAQ and my problem is not listed.

Suggested Changes

@typescript-eslint/no-unused-vars regularly gets one of our most commonly duplicated issues: that it reports on types only used in JSDoc locations. #11208, #10873, #9435, #8902, #5017, #6967, #7944, #8258, etc. I think this is a sign we should document something on the rule page.

#11208 (comment) mentioned jsdoc/no-undefined-types. I think we should at least add an FAQ for it.

Affected URL(s)

https://typescript-eslint.io/rules/no-unused-vars/#faqs

Additional Info

Are there other common "gotcha"s with no-unused-vars we should also add FAQs for?

[Andarist]

For reference, this is how I ended up configuring it: statelyai/xstate#5279