Improvement:

In 1.4.7.1. Enabling service discovery for Submariner document, add a note for the namespace requirement. 

- All clusters in a Submariner-enabled ClusterSet should use identically named namespaces for services that need to be exported and discovered cross-cluster.
- The exported service resides in a namespace with the same name across all clusters in the ClusterSet.

In the above document, the example uses the `nginx` service in the `default` namespace. Similarly, if the service is deployed in the `test-sample` namespace, then the `test-sample` namespace should be available on the target cluster.