Add changelog lint script to docs lint CI job
What does this MR do?
Adds the newly created lint-changelog script to the docs-only job
As discussed in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/14518.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Adds the newly created lint-changelog script to the docs-only job
As discussed in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/14518.