doc: fix a link in api/async_hooks.md
Fixed a link, now it jumps correctly on website.
Checklist
-
documentation is changed or added -
commit message follows commit guidelines
Affected core subsystem(s)
- doc: api/async_hooks.md
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Fixed a link, now it jumps correctly on website.