Caribbean Online Judge added (#2655)

problem-sets-competitive-programming.md

@@ -9,6 +9,7 @@
 
 * [4Clojure](http://www.4clojure.com)
 * [A2 Online Judge](https://a2oj.com)
+* [Caribbean Online Judge](http://coj.uci.cu)
 * [Codeabbey](http://www.codeabbey.com)
 * [Codechef](https://www.codechef.com/contests)
 * [Codecombat](https://codecombat.com)