Merge branch 'mrchrisw/sync-times' into 'master'

Include information on updating mirror synchronization times

+ update_all_mirrors_worker_cron
+ update_all_remote_mirrors_worker_cron

See merge request !763

doc/administration/cron_jobs.md

+# Cron jobs
+
+## Adjusting synchronization times for repository mirroring
+
+>**Notes:**
+- This is an [Enterprise Edition][ee] only feature.
+- For more information on the repository mirroring, see the
+  [user documentation](../workflow/repository_mirroring.md).
+
+You can manually configure the repository synchronization times by setting the
+following configuration values.
+
+Please note that `update_all_mirrors_worker_cron` refers to the worker used for
+pulling changes from a remote mirror while `update_all_remote_mirrors_worker_cron`
+refers to the worker used for pushing changes to the remote mirror.
+
+>**Note:**
+These are cron formatted values. You can use a crontab generator to create these
+values, for example http://www.crontabgenerator.com/.
+
+**Omnibus installations**
+
+```
+gitlab_rails['update_all_mirrors_worker_cron'] = "0 * * * *"
+gitlab_rails['update_all_remote_mirrors_worker_cron'] = "30 * * * *"
+```
+
+**Source installations**
+
+```
+cron_jobs:
+  update_all_mirrors_worker_cron:
+    cron: "0 * * * *"
+  update_all_remote_mirrors_worker_cron:
+    cron: "30 * * * *"
+```
+
+[ee]: https://about.gitlab.com/products

doc/workflow/repository_mirroring.md

@@ -90,5 +90,11 @@ While mirrors update once an hour, you can force an update (either **push** or
 - in the tags page
 - in the **Mirror repository** settings page
 
+## Adjusting synchronization times
+
+You can adjust the synchronization times for the repository mirroring if you
+have access to the GitLab server. For more information, see
+[the administration documentation](../administration/cron_jobs.md#adjusting-synchronization-times-for-repository-mirroring).
+
 [ee-51]: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/51
 [perms]: ../user/permissions.md