A few fixes in Multitenancy document
A few fixes in Multitenancy document

This patch fixes the following items in Multitenancy documentation[1].
  - A security group rule for iSCSI should be ingress because a node is
    connected from ironic conductor.
  - A URL of an article of ML2 plugin configuration has been changed at
    Newton.

[1] http://docs.openstack.org/developer/ironic/deploy/multitenancy.html

Change-Id: I65400cd6717ce4d9c23f41a20f24ee96f9415c4d

SauloAislan/ironic,openstack/ironic,pshchelo/ironic,NaohiroTamura/ironic,openstack/ironic,NaohiroTamura/ironic,SauloAislan/ironic,pshchelo/ironic