clarify data-port for neutron

Update metadata.yaml snippet for neutron-gateway.

Add 'NICs' column to a table on the install-maas page.

Clarify what 'data-port' is and how to configure all MAAS nodes so that
an unused network interface is left in the 'Unconfigured' state.

It is odd to have the user do this but the alternative was to be invasive in
terms of changes, which would result in a high risk of breakage later on. This
entire guide will be revisited and reviewed at a later date.

Closes-Bug: #1833625

Change-Id: I373eb238f10ab31ee43fdea251747393bc95b44b

deploy-guide/source/install-maas.rst

@@ -303,19 +303,19 @@ clicking ``Save changes``.
 Here's a summary of the status of each node we've now added to MAAS, showing
 their names and tags alongside each node's hardware configuration:
 
-+---------------------+-----------+--------+-------+----------+-----------+
-| Node name           | Tag(s)    | CPUs   | RAM   | Drives   | Storage   |
-+=====================+===========+========+=======+==========+===========+
-| os-compute01.maas   | compute   | 2      | 6.0   | 3        | 85.9      |
-+---------------------+-----------+--------+-------+----------+-----------+
-| os-compute02.maas   | compute   | 2      | 6.0   | 3        | 85.9      |
-+---------------------+-----------+--------+-------+----------+-----------+
-| os-compute03.maas   | compute   | 2      | 6.0   | 3        | 85.9      |
-+---------------------+-----------+--------+-------+----------+-----------+
-| os-compute04.maas   | compute   | 2      | 6.0   | 3        | 85.9      |
-+---------------------+-----------+--------+-------+----------+-----------+
-| os-juju01.maas      | juju      | 2      | 4.0   | 1        | 42.9      |
-+---------------------+-----------+--------+-------+----------+-----------+
++---------------------+-----------+------+------+------+--------+---------+
+| Node name           | Tag(s)    | CPUs | NICs | RAM  | Drives | Storage |
++=====================+===========+======+======+======+========+=========+
+| os-compute01.maas   | compute   | 2    | 2    | 6.0  | 3      | 85.9    |
++---------------------+-----------+------+------+------+--------+---------+
+| os-compute02.maas   | compute   | 2    | 2    | 6.0  | 3      | 85.9    |
++---------------------+-----------+------+------+------+--------+---------+
+| os-compute03.maas   | compute   | 2    | 2    | 6.0  | 3      | 85.9    |
++---------------------+-----------+------+------+------+--------+---------+
+| os-compute04.maas   | compute   | 2    | 2    | 6.0  | 3      | 85.9    |
++---------------------+-----------+------+------+------+--------+---------+
+| os-juju01.maas      | juju      | 2    | 1    | 4.0  | 1      | 42.9    |
++---------------------+-----------+------+------+------+--------+---------+
 
 Next steps
 ----------

deploy-guide/source/install-openstack.rst

@@ -211,11 +211,18 @@ going to use this for two applications, ``neutron-gateway`` and ``neutron-api``:
 .. code:: yaml
 
     neutron-gateway:
-      ext-port: 'eth1'
+      data-port: br-ex:eth1
     neutron-api:
       neutron-security-groups: True
 
-First, deploy the gateway:
+The ``data-port`` refers to a network interface that Neutron Gateway will bind
+to. In the above example it is ``eth1`` and it should be an unused interface.
+In the MAAS web UI this interface must be given an *IP mode* of 'Unconfigured'
+(see `MAAS documentation <https://maas.io/docs/commission-nodes#heading--post-commission-configuration>`__
+for guidance). Set all four nodes in this way to ensure that any node is able
+to accommodate Neutron.
+
+Deploy neutron-gateway on machine 0 now:
 
 .. code:: bash