Expose Horizon "DocumentRoot" on host
Expose Horizon "DocumentRoot" on host

This will allow webroot plugin for Let's Encrypt to actually work.
The container has no need to write in this location.

Change-Id: Ia76a0cc007abfdec6f25e1371eb696864f2925fd
Closes-Bug: 1768519

dprince/tripleo-heat-templates,openstack/tripleo-heat-templates,openstack/tripleo-heat-templates,dprince/tripleo-heat-templates