Merge "Add note about src/dest IP version validation"

doc/admin-guide-cloud/source/networking_introduction.rst

@@ -233,12 +233,19 @@ Then, create a firewall that applies the policy.
    .. code-block:: console
 
       $ neutron firewall-rule-create --protocol {tcp,udp,icmp,any} \
+        --source-ip-address SOURCE_IP_ADDRESS \
+        --destination-ip-address DESTINATION_IP_ADDRESS \
         --source-port SOURCE_PORT_RANGE --destination-port DEST_PORT_RANGE \
         --action {allow,deny,reject}
 
    The Networking client requires a protocol value; if the rule is protocol
    agnostic, you can use the ``any`` value.
 
+   .. note::
+
+      When the source or destination IP address are not of the same IP
+      version (for example, IPv6), the command returns an error.
+
 #. Create a firewall policy:
 
    .. code-block:: console