Update README.md

Author: qubvel

README.md

@@ -5,6 +5,10 @@ five other commonly used transfer learning datasets.
 
 The codebase is heavily inspired by the [TensorFlow implementation](https://github.com/tensorflow/tpu/tree/master/models/official/efficientnet).
 
+## Important!
+There was a huge library update **24 of July**. Now efficintnet works with both frameworks: `keras` and `tensorflow.keras`.
+If you have models, trained before that date, to load them, please, use efficientnet of 0.0.4 version (PyPI). You can roll back using `pip install -U efficientnet==0.0.4`.
+
 ## Table of Contents
 
  1. [About EfficientNet Models](#about-efficientnet-models)