Point to correct annotation in federated deployment

Author: Vic Iglesias

docs/user-guide/federation/deployment.md

@@ -75,7 +75,7 @@ if you have 3 registered clusters and you create a Federated Deployment with
 `spec.replicas=3`.
 To modify the number of replicas in each cluster, you can specify
 [FederatedReplicaSetPreference](https://github.com/kubernetes/kubernetes/blob/{{page.githubbranch}}/federation/apis/federation/types.go)
-as an annotation with key `federation.kubernetes.io/replica-set-preferences`
+as an annotation with key `federation.kubernetes.io/deployment-preferences`
 on Federated Deployment.