add free ebook notification

Author: Packt-ITService

Diff for: README.md

@@ -27,3 +27,7 @@ self.label_text.set("Choose One")
 
 * [Kotlin Programming By Example](https://www.packtpub.com/application-development/kotlin-programming-example?utm_source=github&utm_medium=repository&utm_campaign=9781788474542)
 
+### 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/9781788627481">https://packt.link/free-ebook/9781788627481 </a> </p>