OCPBUGS-56989: Swapped out v4InternalSubnet for internalJoinSubnet

Author: dfitzmau

modules/nw-ovn-kubernetes-migration.adoc

@@ -190,7 +190,8 @@ $ oc patch Network.operator.openshift.io cluster --type=merge \
       "ovnKubernetesConfig": {
         "mtu": <mtu>,
         "genevePort": <port>,
-        "v4InternalSubnet": "<ipv4_subnet>",
+        "ipv4":
+          "InternalJoinSubnet": "<ipv4_subnet>",
         "gatewayConfig": {
           "ipForwarding": "<ip_forwarding>",
           "routingViaHost": <gateway_mode>