add free ebook notification

Author: Packt-ITService

README.md

@@ -132,3 +132,7 @@ BiBTeX:
 
 ### Suggestions and Feedback
 [Click here](https://docs.google.com/forms/d/e/1FAIpQLSdy7dATC6QmEL81FIUuymZ0Wy9vH1jHkvpY57OiMeKGqib_Ow/viewform) if you have any feedback or suggestions.
+### Download a free PDF
+
+ <i>If you have already purchased a print or Kindle version of this book, you can get a DRM-free PDF version at no cost.<br>Simply click on the link to claim your free PDF.</i>
+<p align="center"> <a href="https://packt.link/free-ebook/9781838826048">https://packt.link/free-ebook/9781838826048 </a> </p>