Correct multi-cluster README.md GitRepo manifests to use 'fleet-default' namespace

tests/expected/multi-cluster/helm-kustomize/bundle.yaml

@@ -4,7 +4,7 @@ metadata:
   labels:
     fleet.cattle.io/commit: fake
   name: test
-  namespace: fleet-local
+  namespace: fleet-default
 spec:
   helm:
     chart: https://github.com/rancher/fleet-examples/releases/download/example/guestbook-0.0.0.tgz
@@ -182,7 +182,7 @@ spec:
       apiVersion: fleet.cattle.io/v1alpha1
       metadata:
         name: helm-kustomize
-        namespace: fleet-local
+        namespace: fleet-default
       spec:
         repo: https://github.com/rancher/fleet-examples
         paths: