Add Binder and Colab badges and links.

This gives readers more options of where and how to view and evaluate
the Jupyter notebooks, along with colorful badges on the main page.

README.md

@@ -1,6 +1,14 @@
 Machine Learning Notebooks
 ==========================
 
+[![Binder][binder-badge]][binder-url]
+[![Google Colab][colab-badge]][colab-url]
+
+[binder-badge]: https://mybinder.org/badge.svg
+[binder-url]: https://mybinder.org/v2/gh/ageron/handson-ml/master?filepath=index.ipynb
+[colab-badge]: https://colab.research.google.com/assets/colab-badge.svg
+[colab-url]: https://colab.research.google.com/github/ageron/handson-ml/blob/master/index.ipynb
+
 This project aims at teaching you the fundamentals of Machine Learning in
 python. It contains the example code and solutions to the exercises in my O'Reilly book [Hands-on Machine Learning with Scikit-Learn and TensorFlow](http://shop.oreilly.com/product/0636920052289.do):
 
@@ -9,7 +17,9 @@ python. It contains the example code and solutions to the exercises in my O'Reil
 Simply open the [Jupyter](http://jupyter.org/) notebooks you are interested in:
 
 * Using [jupyter.org's notebook viewer](http://nbviewer.jupyter.org/github/ageron/handson-ml/blob/master/index.ipynb)
-    * note: [github.com's notebook viewer](https://github.com/ageron/handson-ml/blob/master/index.ipynb) also works but it is slower and the math formulas are not displayed correctly,
+  * or [Binder](https://mybinder.org/v2/gh/ageron/handson-ml/master?filepath=index.ipynb)
+  * or [Google Colab](https://colab.research.google.com/github/ageron/handson-ml/blob/master/index.ipynb)
+  * or [github.com's notebook viewer](https://github.com/ageron/handson-ml/blob/master/index.ipynb), which works, but it is slower and the math formulas are not displayed correctly,
 * or by cloning this repository and running Jupyter locally. This option lets you play around with the code. In this case, follow the installation instructions below.
 
 # Installation