Add "Warning" for "Create a port" section

As an OpenStack cloud end user, can provision his own resources within
the limits set by cloud administrators. But "Create a port" is under
"Admin" tab, and can manage other user's resources, so add "Warning"
for the "Create a port" section in "OpenStack End User Guide".

Closes-Bug: #1589183
Change-Id: Ibf39c666fc86c49d5013fcc8c1e28ddca8581d88

doc/admin-guide/source/dashboard.rst

@@ -32,4 +32,6 @@ for your operating system.
   `Launch and manage instances
   <http://docs.openstack.org/user-guide/dashboard_launch_instances.html>`__.
   in the OpenStack End User Guide.
-
+- To create and manage ports, see the `Create and manage networks
+  <http://docs.openstack.org/user-guide/dashboard_create_networks.html#create-a-port>`__
+  section of the OpenStack End User Guide.

doc/user-guide/source/dashboard_create_networks.rst

@@ -114,6 +114,11 @@ from the :guilabel:`Network Topology` tab.
 Create a port
 ~~~~~~~~~~~~~
 
+.. warning::
+
+  Creating and managing ports requires administrator privileges.
+  Contact an administrator before adding or changing ports.
+
 #. Log in to the dashboard.
 
 #. Select the appropriate project from the drop-down menu at the top left.