Doc change for multiple iSCSI port support in 3PAR

Documentation for DocImpact in https://review.openstack.org/#/c/36535/

Fixes: bug 1200372

Change-Id: I0297ec84e2272abb1c3d18f4857e0ef98a6bd8fd
Merge "Doc change for multiple iSCSI port support in 3PAR"