The documentation [1] should report that podSelector and namespaceSelector are not allowed in MultiNetworkPolicy when the NetworkAttachDefinition is of type localnet or layer2, this is visible only in the source code [2][3] and when tried in a cluster since the following error is visible in the `ovnkube-controller` container:

~~~
E0127 20:17:19.192389 1119416 obj_retry.go:671] Failed to update *v1beta1.MultiNetworkPolicy, old=namespace/policy, new=namespace/policy, error: invalid ingress peer {nil &LabelSelector{MatchLabels:map[string]string{kubernetes.io/metadata.name: namespace,},MatchExpressions:[]LabelSelectorRequirement{},} <nil>} in multi-network policy policy; IPAM-less networks can only have `ipBlock` peers
~~~ 

[1] https://docs.openshift.com/container-platform/4.17/networking/multiple_networks/secondary_networks/configuring-multi-network-policy.html
[2] https://github.com/openshift/ovn-kubernetes/blob/44f5d08bf2201bdbff7acb7e6a57bbdd7f2d0f19/go-controller/pkg/ovn/base_network_controller_multipolicy.go#L133
[3] https://github.com/openshift/ovn-kubernetes/blob/master/go-controller/pkg/util/multi_network.go#L1341

4.17, 1.16

Clarify in the official doc the use of the selectors in multi-policy when secondary OVN is used