kubefed tutorial: add creating the default ns (#3105)

Currently kubefed does not create the default namespace, therefore anyone
following this doc today will hit this issue. Adding a few comments to bridge
that gap until the bug is fixed.

Signed-off-by: Ahmet Alp Balkan <ahmetb@google.com>

docs/tutorials/federation/set-up-cluster-federation-kubefed.md

@@ -123,6 +123,20 @@ The domain suffix specified in `--dns-zone-name` must be an existing
 domain that you control, and that is programmable by your DNS provider.
 It must also end with a trailing dot.
 
+Once the federation control plane is initialized, query the namespaces:
+
+```shell
+kubectl get namespace --context=fellowship
+```
+
+If you do not see the `default` namespace listed (this is due to a
+[bug](https://github.com/kubernetes/kubernetes/issues/33292)). Create it
+yourself with the following command:
+
+```shell
+kubectl create namespace default --context=fellowship
+```
+
 The machines in your host cluster must have the appropriate permissions
 to program the DNS service that you are using. For example, if your
 cluster is running on Google Compute Engine, you must enable the