replace dead link

Fix for [computer-science/issues/825](#825)

README.md

@@ -355,7 +355,7 @@ Courses | Duration | Effort | Prerequisites
 [Parallel Programming](https://www.coursera.org/learn/parprog1)| 4 weeks | 6-8 hours/week | Scala programming
 [Compilers](https://www.edx.org/course/compilers) | 9 weeks | 6-8 hours/week | none
 [Introduction to Haskell](https://www.seas.upenn.edu/~cis194/fall16/)| 14 weeks | - | -
-[Learn Prolog Now!](http://lpn.swi-prolog.org/lpnpage.php?pageid=top)| 12 weeks | - | -
+[Learn Prolog Now!](http://www.learnprolognow.org/lpnpage.php?pageid=online)| 12 weeks | - | -
 [Software Debugging](https://www.udacity.com/course/software-debugging--cs259)| 8 weeks | 6 hours/week | Python, object-oriented programming
 [Software Testing](https://www.udacity.com/course/software-testing--cs258) | 4 weeks | 6 hours/week | Python, programming experience
 [Software Architecture & Design](https://www.udacity.com/course/software-architecture-design--ud821)| 8 weeks | 6 hours/week | software engineering in Java