[sahara doc fix] guest requirements doc
[sahara doc fix] guest requirements doc

Change-Id: I29c29ed090c128e5996894a426f8f020ff83e4cc
Partial-Bug: 1490687

openstack/sahara,tellesnobrega/sahara,openstack/sahara,zhangjunli177/sahara,zhangjunli177/sahara,egafford/sahara,zhangjunli177/sahara,tellesnobrega/sahara,egafford/sahara