Merge branch 'mw/events-api-doc-add-approved' into 'master'

Add `approved` as action type on events API

See merge request gitlab-org/gitlab!47273

doc/api/events.md

@@ -12,6 +12,7 @@ info: To determine the technical writer assigned to the Stage/Group associated w
 
 Available action types for the `action` parameter are:
 
+- `approved`
 - `created`
 - `updated`
 - `closed`