Small Horizon configuration docs fix
Small Horizon configuration docs fix

Push users to configure Horizon within user_varables.yml rather than messing
around with files in the playbooks directories.

Change-Id: I82dac6e3c0d0206e6e4fe3b98b3ab0ae56b24f64

open-switch/infra_openstack-ansible,major/openstack-ansible,manuelfelipe/openstack-ansible,major/openstack-ansible,sti-jans/openstack-ansible,mancdaz/openstack-ansible,yanyao/openstack-deployment-liberty,achekunov/openstack-ansible,weezer/openstack-ansible,yanyao/openstack-deployment-liberty,manuelfelipe/openstack-ansible,BjoernT/os-ansible-deployment,yanyao/newton,openstack/openstack-ansible,cfarquhar/openstack-ansible,jpmontez/openstack-ansible,antonym/openstack-ansible,shane-c/openstack-ansible,achekunov/openstack-ansible,manuelfelipe/openstack-ansible,sti-jans/openstack-ansible,git-harry/os-ansible-deployment,stackforge/os-ansible-deployment,robb-romans/openstack-ansible,sti-jans/openstack-ansible,yanyao/newton,BjoernT/os-ansible-deployment,os-cloud/os-ansible-deployment,jpmontez/os-ansible-deployment,Logan2211/openstack-ansible,git-harry/os-ansible-deployment,cfarquhar/openstack-ansible,open-switch/infra_openstack-ansible,Logan2211/openstack-ansible,shane-c/openstack-ansible,mrda/openstack-ansible,yanyao/openstack-deployment-liberty,mrda/openstack-ansible,yanyao/openstack-ansible,antonym/openstack-ansible,stackforge/os-ansible-deployment,achekunov/openstack-ansible,jpmontez/os-ansible-deployment,robb-romans/openstack-ansible,shane-c/openstack-ansible,antonym/openstack-ansible,weezer/openstack-ansible,jpmontez/os-ansible-deployment,cloudnull/os-ansible-deployment,mrda/openstack-ansible,BjoernT/openstack-ansible,bunchc/openstack-ansible,openstack/openstack-ansible,BjoernT/openstack-ansible,open-switch/infra_openstack-ansible,mancdaz/openstack-ansible,os-cloud/os-ansible-deployment,git-harry/os-ansible-deployment,cloudnull/os-ansible-deployment,yanyao/openstack-ansible,BjoernT/os-ansible-deployment,jpmontez/openstack-ansible,major/os-ansible-deployment,bunchc/openstack-ansible,jpmontez/openstack-ansible,major/os-ansible-deployment