Add version that the mermaid support was introduced (!15688) · Merge requests · GitLab.org / GitLab FOSS · GitLab

Achilleas Pipinellis - OOO until November 25th (parental leave) requested to merge docs/mermaid-gl-version into master Dec 01, 2017

What does this MR do?

Clarify in the docs when the mermaid markdown support was introduced https://gitlab.com/gitlab-org/gitlab-ce/issues/40734#note_49708795.