Merge branch 'housekeeping-doc' into 'master'

Add housekeeping feature documentation

Add documentation about the new housekeeping feature in the project settings page.

See merge request !2371

doc/README.md

@@ -69,6 +69,7 @@
 - [Reply by email](incoming_email/README.md) Allow users to comment on issues and merge requests by replying to notification emails.
 - [Migrate GitLab CI to CE/EE](migrate_ci_to_ce/README.md) Follow this guide to migrate your existing GitLab CI data to GitLab CE/EE.
 - [Git LFS configuration](workflow/lfs/lfs_administration.md)
+- [Housekeeping](administration/housekeeping.md) Keep your Git repository tidy and fast.
 - [GitLab Performance Monitoring](monitoring/performance/introduction.md) Configure GitLab and InfluxDB for measuring performance metrics
 
 ## Contributor documentation

doc/administration/housekeeping.md

+# Housekeeping
+
+_**Note:** This feature was [introduced][ce-2371] in GitLab 8.4_
+
+---
+
+The housekeeping function runs [`git gc`][man] on the current project Git
+repository.
+
+`git gc` runs a number of housekeeping tasks, such as compressing file
+revisions (to reduce disk space and increase performance) and removing
+unreachable objects which may have been created from prior invocations of
+`git add`.
+
+You can find this option under your **[Project] > Settings**.
+
+---
+
+![Housekeeping settings](img/housekeeping_settings.png)
+
+[ce-2371]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/2371 "Housekeeping merge request"
+[man]: https://www.kernel.org/pub/software/scm/git/docs/git-gc.html "git gc man page"