[comment]: # ( Copyright Contributors to the Open Cluster Management project )
ManagedClusterSet defines a group of ManagedClusters that user's workload can run on.
Put label cluster.open-cluster-management.io/clusterset=<clusterset_name> on a ManagedCluster to assign it to a ManagedClusterSet.
To remove a ManagedCluster from a ManagedClusterSet, just remove the label cluster.open-cluster-management.io/clusterset from the ManagedCluster.
User must have a RBAC rule CREATE on a virtual subresource of managedclustersets/join to add/remove label cluster.open-cluster-management.io/clusterset to/from a ManagedCluster. In order to update this label on a ManagedCluster, user must have the permission on both the old and new ManagedClusterSet.