OpenShift 4.14 NMState operator documentation has the following statements.
These statement refer to "Creating a manifest object that includes a customized br-ex bridge".

• https://docs.redhat.com/en/documentation/openshift_container_platform/4.14/html/networking/kubernetes-nmstate#virt-example-nmstate-IP-management-dns_k8s-nmstate-updating-node-network-config

  You cannot use the br-ex bridge, an OVN-Kubernetes-managed Open vSwitch bridge, as the interface when configuring DNS resolvers unless you manually configured a customized br-ex bridge.
  For more information, see "Creating a manifest object that includes a customized br-ex bridge" in the Deploying installer-provisioned clusters on bare metal document or the Installing a user-provisioned cluster on bare metal document. 

• https://docs.redhat.com/en/documentation/openshift_container_platform/4.14/html/networking/kubernetes-nmstate#virt-example-nmstate-IP-management-static-routing_k8s-nmstate-updating-node-network-config

  You cannot use the OVN-Kubernetes br-ex bridge as the next hop interface when configuring a static route unless you manually configured a customized br-ex bridge.
  For more information, see "Creating a manifest object that includes a customized br-ex bridge" in the Deploying installer-provisioned clusters on bare metal document or the Installing a user-provisioned cluster on bare metal document.  

However, OCP 4.14 documentation doesn't have "Creating a manifest object that includes a customized br-ex bridge" document.
"Creating a manifest object that includes a customized br-ex bridge" document is available only on 4.16 and later:

• OCP 4.16 : 3.4. Creating a manifest object that includes a customized br-ex bridge
  https://docs.redhat.com/en/documentation/openshift_container_platform/4.17/html/installing_on_bare_metal/installing-bare-metal-network-customizations#creating-manifest-file-customized-br-ex-bridge_installing-bare-metal-network-customizations

Cannot we configure DNS resolvers or static routes on br-ex on OCP 4.14?
Should we remove the reference to the "Creating a manifest object that includes a customized br-ex bridge" from OCP 4.14 documents?

FYI, OCP 4.13, 4.14 and 4.15 documentation have the same issue.