Add warning interface names with dashes

Change-Id: Ie86849fbfbdef0e20a89f0fc3c6c617bc4ae23ff
Closes-Bug: #1711757

doc/production-architecture-guide.rst

@@ -80,6 +80,12 @@ In Kolla operators should configure following network interfaces:
   with the bare metal cloud hosts in order to provide DHCP leases with
   PXE boot options. Defaults to ``network_interface``.
 
+.. WARNING::
+
+   Ansible facts does not recognize interface names containing dashes,
+   in example ``br-ex`` or ``bond-0`` cannot be used because ansible will read
+   them as ``br_ex`` and ``bond_0`` respectively.
+
 Docker configuration
 ====================