docs: documenting async hooks features
Checklist
-
documentation is changed or added -
commit message follows commit guidelines
Affected core subsystem(s)
- async hooks
- docs
This is a continuation on #12953 it should "fix" all the suggestions.
It took me 3 hours fix all the issues, so I would like if nits are done by you in a followup PR I simply don't have this much time. Also please be very specific with the suggestions, as in replace "this" with "this".