Improve docs for promote quick actions
This is the docs for promote issue to epic: https://docs.gitlab.com/ee/user/group/epics/#promoting-an-issue-to-an-epic
This should be improved to explain how to actually use the feature (via quick actions). And it should link to the quick actions page.
Also it should include something like:
> [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/issues/7730) in [GitLab Ultimate](https://about.gitlab.com/pricing/) 10.6.
Edited by Victor Wu