Update Game Design specialization

Bump to new version

Author: t-miller

README.md

@@ -418,7 +418,7 @@ Courses | Duration | Effort | Prerequisites
 [Fullstack Open](https://fullstackopen.com/en) | 12 weeks | 6 hours/week | programming
 [Data Science (Specialization)](https://www.coursera.org/specializations/jhu-data-science) | 43 weeks | 1-6 hours/week | none
 [Functional Programming in Scala (Specialization)](https://www.coursera.org/specializations/scala) | 29 weeks | 4-5 hours/week | One year programming experience
-[Game Design and Development (Specialization)](https://www.coursera.org/specializations/game-development) | 6 months | 5 hours/week | programming, interactive design
+[Game Design and Development with Unity 2020 (Specialization)](https://www.coursera.org/specializations/game-design-and-development) | 6 months | 5 hours/week | programming, interactive design
 
 ## Final project