Merge branch 'add-date-for-metrics' into 'master'

Add in release when metrics report was added

See merge request gitlab-org/gitlab-ce!28274

doc/ci/yaml/README.md

@@ -1510,6 +1510,8 @@ be automatically shown in merge requests.
 
 ##### `artifacts:reports:metrics` **[PREMIUM]**
 
+> Introduced in GitLab 11.10.
+
 The `metrics` report collects [Metrics](../../ci/metrics_reports.md)
 as artifacts.