Fixed broken links

The broken link for make_image_classifier and colab gist for tf2_image_retraining.ipynb has been updated in TF documentation.
Please have a look and do the needful. Thank you!

Author: sushreebarsa

examples/image_retraining/README.md

@@ -1,12 +1,12 @@
 WARNING: This code is deprecated.
 
 The `retrain.py` tool from this directory has been replaced by the
-[`make_image_classifier`](https://github.com/tensorflow/hub/tree/master/tensorflow_hub/tools/make_image_classifier)
+[`make_image_classifier`](https://www.tensorflow.org/hub/tutorials/tf2_image_retraining)
 tool that gets
 [installed](https://www.tensorflow.org/hub/installation) as a command-line tool
 by the PIP package `tensorflow-hub[make_image_classifier]`.
 The new tool uses TensorFlow 2 and supports fine-tuning.
 
 The Colab notebook
-[tf2_image_retraining.ipynb](https://colab.research.google.com/github/tensorflow/hub/blob/master/examples/colab/tf2_image_retraining.ipynb)
+[tf2_image_retraining.ipynb](https://colab.research.google.com/github/tensorflow/docs/blob/master/site/en/hub/tutorials/tf2_image_retraining.ipynb)
 explains the basic technique behind that tool: transfer learning with TF Hub.