Removes a reference that doesn't exist anymore in the install doc
Following https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/2766#note_3637751 the "Update configuration files" section isn't present in the install doc anymore
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Following https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/2766#note_3637751 the "Update configuration files" section isn't present in the install doc anymore