message: update image_retraining link in toc to point to hub location
diff: @@ -49,8 +49,7 @@ toc:
  - title: Image recognition
  path: /tutorials/images/image_recognition
  - title: Image retraining
  - path: https://github.com/tensorflow/hub/tree/master/docs/tutorials/image_retraining.md
  - status: external
  + path: /hub/tutorials/image_retraining
  - title: Convolutional Neural Networks
  path: /tutorials/images/deep_cnn
  