Add warning about interface name change from hw_machine_type

Author: MoteHue

doc/source/operations/rocky-linux-9.rst

@@ -83,8 +83,17 @@ Make the following changes to your Kayobe configuration:
      hw_machine_type = x86_64=q35
      num_pcie_ports = 16
 
-  This change does not need to be applied before migrating to Rocky Linux 9, but it should cause no harm to do so.
-  Note that this will not affect existing VMs, only newly created VMs.
+  This change does not need to be applied before migrating to Rocky Linux 9,
+  but it is likely to best place to do so.
+
+  .. warning::
+
+     This change will cause the interface names to change on any new VMs
+     launched with images that do not specify a hw_machine_type already.
+     Existing VMs will not be affected, but a rebuild will have the names
+     changed. Customers should be informed of this in case they have any
+     tooling that relies on interface names within their VMs.
+
 
 Routing rules
 -------------