Update SR-IOV configuration admin docs
Update SR-IOV configuration admin docs

Mellanox ConnectX-3 network adapter family requires
additional configuration in Neutron sriov agent when
using a dual port adapter.

Updated the relevant document to reflect the needed
change to allow Neutron sriov agent to properly utilize
the generated VFs.

Change-Id: I427a497940efe6ff60338390a262d178f834dc8f

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