Update README.md

Author: nmheim

README.md

@@ -12,4 +12,4 @@
 This repository contains all the course materials for the master course
 _**Scientific Programming in Julia**_ taught at the Czech Techincal University
 in Prague. You can find more information on the official
-[course website](https://juliateachingctu.github.io/Scientific-Programming-in-Julia/dev).
+[course website](https://juliateachingctu.github.io/Scientific-Programming-in-Julia/stable).