Update repository_mirroring.md as per...

Update repository_mirroring.md as per https://gitlab.com/gitlab-org/gitlab-ee/issues/10361#note_198445760

doc/workflow/repository_mirroring.md

@@ -102,7 +102,7 @@ The repository will push soon. To force a push, click the appropriate button.
 > - [Added Git LFS support](https://gitlab.com/gitlab-org/gitlab-ee/issues/10871) in [GitLab Starter](https://about.gitlab.com/pricing/) 11.11.
 
 NOTE: **Note:** This feature [is available for free](https://gitlab.com/gitlab-org/gitlab-ee/issues/10361) to
-GitLab.com users until September 22nd, 2019.
+GitLab.com users until March 22nd, 2020.
 
 You can set up a repository to automatically have its branches, tags, and commits updated from an
 upstream repository.