Add a prompt to update doc comments, use it to improve Quick Pick/Input documentation (#275935)

* Add a prompt to update doc comments, use it to improve Quick Pick/Input documentation

* Update .github/prompts/doc-comments.prompt.md

Co-authored-by: Joaquín Ruales <[email protected]>

* Update .github/prompts/doc-comments.prompt.md

Co-authored-by: Joaquín Ruales <[email protected]>

* Add max line length and 'cleanup' mode.

* Add linting rule

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Co-authored-by: Joaquín Ruales <[email protected]>