Add Redis University Course (#6305)

* Add Redis University Course

* Fix lint validation trailing slash

* Ammend PR comment

courses/free-courses-en.md

@@ -286,6 +286,7 @@
 
 * [MongoDB University](https://university.mongodb.com) - MongoDB, Inc. (email address *required*)
 * [Neo4j Graph Database Tutorial](https://www.youtube.com/playlist?list=PLqfPEK2RTgChcOZ6qHgSfwiBPCz2Bzdjh) - Satish C J (YouTube)
+* [Redis University](https://university.redis.com) - Redis Inc. *(email address required)*
 
 
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