Add housekeeping feature documentation

doc/README.md

@@ -67,6 +67,7 @@
 - [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.
 
 ## Contributor documentation
 

doc/administration/housekeeping.md

+# Housekeeping
+
+## Introduction
+
+The housekeeping function runs `git gc` 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.
+
+Users are encouraged to run this task on a regular basis to maintain good disk space utilization and good operating performance.
+
+## Where can I find it?
+
+Just go to your project settings page and you will find the housekeeping function below the project settings form.