update the README to contain ppc64le dockerfile

examples/v1/mnist_with_summaries/README.md

@@ -6,11 +6,16 @@ for integrating with other components like Katib.
 
 The source code is borrowed from TensorFlow tutorials [here](https://github.com/tensorflow/tensorflow/blob/master/tensorflow/examples/tutorials/mnist/mnist_with_summaries.py).
 
-To build this image:
+To build this image on x86_64:
 ```shell
 docker build -f Dockerfile -t kubeflow/tf-mnist-with-summaries:1.0 ./
 ```
+On ppc64le, run as:
+```shell
+docker build -f Dockerfile.ppc64le -t kubeflow123/tf-mnist-with-summaries:1.0 ./
+```
 
 Usage:
 1. Add the persistent volume and claim: `kubectl apply -f tfevent-volume/.`
 1. Deploy the TFJob: `kubectl apply -f tf_job_mnist.yaml`
+   * If on ppc64le, please update tf_job_mnist.yaml to use the image of ppc64le firstly.