In the current docs, a nit was found according to Or:

ClusterUserDefinedNetwork CRs should not be created in the default namespace. This can result in no isolation and, as a result, could introduce security risks to the clusteThe CUDN CRD is cluster scope ot cannot be created in a namespase
It should say CUDN should not select the default namespace
Sam goes for opeshift-* namespaces

This should be addressed on Day 1 of the 4.18 release.