Add Health Check Documentation
What does this MR do?
Adds documentation for: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/10416
What are the relevant issue numbers?
Closes #30649 (closed)
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Adds documentation for: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/10416
Closes #30649 (closed)