add $5 campaign

Author: Packt-ITService

README.md

@@ -1,3 +1,8 @@
+## $5 Tech Unlocked 2021!
+[Buy and download this product for only $5 on PacktPub.com](https://www.packtpub.com/)
+-----
+*The $5 campaign         runs from __December 15th 2020__ to __January 13th 2021.__*
+
 # C# Data Structures and Algorithms
 This is the code repository for [C# Data Structures and Algorithms](https://www.packtpub.com/application-development/c-data-structures-and-algorithms-0?utm_source=github&utm_medium=repository&utm_campaign=9781788833738), published by [Packt](https://www.packtpub.com/?utm_source=github). It contains all the supporting project files necessary to work through the book from start to finish.
 ## About the Book