Update merge request versions documentation with new screenshots (!6454) · Merge requests · GitLab.org / GitLab FOSS · GitLab

Dmytro Zaporozhets (DZ) requested to merge dz-improve-mr-versions-doc into master Sep 21, 2016

For #13570 (closed) based on https://gitlab.com/gitlab-org/gitlab-ce/issues/21427