Merge pull request #1190 from switchhax/master

Add "4Clojure.com" to the tutorial section

free-programming-interactive-tutorials-en.md

@@ -39,6 +39,7 @@
 
 
 ### Clojure
+* [4Clojure - Koans](https://www.4clojure.com/)
 * [Clojure Koans](http://clojurekoans.com/)
 * [ClojureScript Koans](http://clojurescriptkoans.com/)
 * [Try Clojure](http://tryclj.com/)