Update databases.md
Created by: zzet
related https://github.com/gitlabhq/gitlabhq/issues/2786#issuecomment-15353820
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Created by: zzet
related https://github.com/gitlabhq/gitlabhq/issues/2786#issuecomment-15353820