Warn not to use console.log when verifying. #63

Author: timoxley

problems/async_loops/problem.md

@@ -34,6 +34,8 @@ The order of the users should match the order of supplied user ids. Because this
 ## Hint
 
 * You don't need to use a sort to maintain ordering.
+* Using console.log will affect verification. Only use console.log
+when using `functional-javascript run`.
 
 ## Boilerplate
 ```js