Docs for merge train visualization
What does this MR do and why?
This MR updates the merge train docs for the merge train visualization feature. It adds a new task topic to view a merge train, and also updates the existing topic to remove a merge request from a merge train.
Review app link: https://main-ee-162117.docs.gitlab-review.app/ee/ci/pipelines/merge_trains.html
Resolves: #476152 (closed)
Edited by Lysanne Pinto