add free ebook notification

Author: Packt-ITService

README.md

@@ -41,3 +41,7 @@ For optimal student experience, the following hardware requirements is recommend
 * Anaconda Distribution
 * pip
 
+### 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/9781838551216">https://packt.link/free-ebook/9781838551216 </a> </p>