Fixed invalid YAML in GKE self managed flow

This fixes the error:

```
error: error parsing ../resources/rbac.yaml: error converting
YAML to JSON: yaml: line 9: did not find expected key
```

docs/deploy/resources/rbac.yaml

@@ -25,6 +25,7 @@ roleRef:
   apiGroup: rbac.authorization.k8s.io
   kind: Role
   name: system:controller:glbc
+subjects:
 - kind: ServiceAccount
   name: glbc
   namespace: kube-system