add Django Channels book

README.md

@@ -157,6 +157,7 @@
 * [Django for Beginners: Build websites with Python and Django](https://djangoforbeginners.com/)
 * [REST APIs with Django: Build web APIs with Python and Django](https://restapiswithdjango.com/)
 * [Build Your First Website with Django 2.1](https://transactions.sendowl.com/stores/9897/130290)
+* [Develop a Real-Time Taxi App with Django Channels and Angular](https://testdriven.io/courses/real-time-app-with-django-channels-and-angular/?source=e4245ba649f3)
 
 > Django 2.0