chore: correct internal link in v30 notes

Updated the documentation to link to the correct index for exapps management.

Signed-off-by: Josh <[email protected]>

Author: joshtrichards

admin_manual/release_notes/upgrade_to_30.rst

@@ -45,7 +45,7 @@ Starting with Nextcloud 30.0.12 the monitoring app was adjusted to count the act
 AppApi (app_app) is now a default app
 -------------------------------------
 
-Starting with Nextcloud 30.0.1, the AppApi app is included and enabled by default. See :doc:`../exapps_management` for details.
+Starting with Nextcloud 30.0.1, the AppApi app is included and enabled by default. See :doc:`../exapps_management/index` for details.
 
 This app can be disabled in the standard manner via the *Apps* menu if you do not expect to use AppApi integrations in the near future.