Mention how we use gitlab-triage

CONTRIBUTING.md

@@ -376,8 +376,14 @@ on those issues. Please select someone with relevant experience from the
 [GitLab team][team]. If there is nobody mentioned with that expertise look in
 the commit history for the affected files to find someone.
 
+We also use [GitLab Triage] to automate some triaging policies. This is
+currently setup as a [scheduled pipeline] running on the [`gl-triage`] branch.
+
 [described in our handbook]: https://about.gitlab.com/handbook/engineering/issue-triage/
 [issue bash events]: https://gitlab.com/gitlab-org/gitlab-ce/issues/17815
+[GitLab Triage]: https://gitlab.com/gitlab-org/gitlab-triage
+[scheduled pipeline]: https://gitlab.com/gitlab-org/gitlab-ce/pipeline_schedules/3732/edit
+[`gl-triage`]: https://gitlab.com/gitlab-org/gitlab-ce/tree/gl-triage
 
 ### Feature proposals