Add pretrained checkpoints and TFHub links

PiperOrigin-RevId: 280321302

official/vision/image_classification/README.md

@@ -19,9 +19,14 @@ uses a ResNet50 model implemented in [`resnet_model.py`](./resnet_model.py).
 To use
 either dataset, make sure that you have the latest version of TensorFlow
 installed and
-[add the models folder to your Python path](/official/#running-the-models),
-otherwise you may encounter an error like `ImportError: No module named
-official.resnet`.
+[add the models folder to your Python path](/official/#running-the-models).
+
+### Pretrained Models
+
+* [ResNet50 Checkpoints](https://storage.googleapis.com/cloud-tpu-checkpoints/resnet/resnet50.tar.gz)
+
+* ResNet50 TFHub: [feature vector](https://tfhub.dev/tensorflow/resnet_50/feature_vector/1)
+and [classification](https://tfhub.dev/tensorflow/resnet_50/classification/1)
 
 ### CIFAR-10
 
@@ -43,7 +48,7 @@ location with the `--data_dir` flag, like:
 python resnet_cifar_main.py --data_dir=/path/to/cifar
 ```
 
-### ImageNet
+### ImageNet Training
 
 Download the ImageNet dataset and convert it to TFRecord format.
 The following [script](https://github.com/tensorflow/tpu/blob/master/tools/datasets/imagenet_to_gcs.py)