Update vpnaas-scenario docs
Update vpnaas-scenario docs

Add different configs depending upon the Linux distribution.

Change-Id: If50421ec722c89c2f37776d0df66de8a583ddb48

noironetworks/neutron,openstack/neutron,mahak/neutron,mahak/neutron,openstack/neutron,mahak/neutron,openstack/neutron,noironetworks/neutron