Add more details to git server documentation

Specify what is running on the new git server, add basic
SELinux, replication and jeepyb details.

Also add to list of systems.

Change-Id: I027fa00cf6b6cee8b73fa844983cc82d465617ef

doc/source/git.rst

@@ -15,6 +15,8 @@ At a Glance
 :Puppet:
   * :file:`modules/cgit`
   * :file:`modules/openstack_project/manifests/git.pp`
+:Configuration:
+  * :file:`modules/openstack_project/files/git/cgitrc`
 :Projects:
   * http://git.zx2c4.com/cgit/
 :Bugs:
@@ -24,5 +26,14 @@ At a Glance
 Overview
 ========
 
+The OpenStack git repositories are hosted on this server and served up via
+https using cgit and via git:// by git-daemon.
+
 Apache is running on a CentOS 6 system with the EPEL repository that includes
-the cgit packages.
+the cgit package. SELinux is enabled and requires restorecon to be run against
+/var/lib/git to set the appropriate SELinux security context, this is handled
+by puppet.
+
+The jeepyb script create-cgitrepos runs against projects.yaml to generate the
+/etc/cgitrepos file listing all the git repositories. The git repositories are
+synced from the Gerrit server.

doc/source/systems.rst

@@ -21,3 +21,4 @@ Major Systems
    static
    lists
    wiki
+   git