Update events to reflect shared state

Events was previously marked as exclusive to user_profile,
but actually a number of different services emit events and
this change reflects the different categories involved.

db/docs/events.yml

@@ -5,7 +5,13 @@ classes:
 - PushEvent
 feature_categories:
 - user_profile
-description: Stores user generated events.
+- wiki
+- team_planning
+- design_management
+- code_review_workflow
+- source_code_management
+- user_management
+description: Stores events created by users interacting with various product features
 introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/commit/a847501fd2ffc1c4becc7d0d352d80168d9b3568
-milestone: "<6.0"
+milestone: "2.2"
 gitlab_schema: gitlab_main