Change mpi example docker hub registry

Author: andreyvelich

examples/v1beta1/README.md

@@ -393,5 +393,5 @@ docker.io/inaccel/jupyter:lab
 - MPI operator horovod mnist example, [source](https://github.com/kubeflow/mpi-operator/tree/master/examples/horovod).
 
 ```
-docker.io/kubeflowkatib/horovod-mnist
+docker.io/kubeflow/mpi-horovod-mnist
 ```

examples/v1beta1/mpijob-horovod.yaml

@@ -53,7 +53,7 @@ spec:
                   sidecar.istio.io/inject: "false"
               spec:
                 containers:
-                  - image: docker.io/kubeflowkatib/horovod-mnist
+                  - image: docker.io/kubeflow/mpi-horovod-mnist
                     name: mpi-launcher
                     command:
                       - mpirun
@@ -93,7 +93,7 @@ spec:
                   sidecar.istio.io/inject: "false"
               spec:
                 containers:
-                  - image: docker.io/kubeflowkatib/horovod-mnist
+                  - image: docker.io/kubeflow/mpi-horovod-mnist
                     name: mpi-worker
                     resources:
                       limits: