Add guide to auto mount /run as shared

Add guide: auto mount /run as shared upon startup to quickstart guide

Change-Id: Icd6ad399a97e15ff357e75fa52e9646e78d09e21

doc/quickstart.rst

@@ -120,12 +120,21 @@ the drop-in unit file as follows, reload and restart the docker service:
     systemctl daemon-reload
     systemctl restart docker
 
-For Ubuntu 14.04 which uses upstart instead of systemd, run the following:
+For Ubuntu 14.04 which uses upstart and other non-systemd distros,
+run the following:
 
 ::
 
     mount --make-shared /run
 
+For mounting ``/run`` as shared upon startup, add that command to
+``/etc/rc.local``
+
+::
+
+    # Edit /etc/rc.local to add:
+    mount --make-shared /run
+
 .. note:: If centos/fedora/oraclelinux container images are built on an Ubuntu
   host, the backend storage driver must not be AUFS (see the known issues in
   :doc:`image-building`).