extension documentation discoverability
I know that extension documentation is covered here: https://docs.civicrm.org/dev/en/latest/documentation/extensions/
For the purposes of discoverability, I think it would be worth pointing to that from a stub paragraph here: https://docs.civicrm.org/dev/en/latest/extensions/, maybe https://docs.civicrm.org/dev/en/latest/extensions/documentation