Update article.md

Remove comma.

Author: paroche

1-js/06-advanced-functions/12-arrow-functions/article.md

@@ -4,7 +4,7 @@ Let's revisit arrow functions.
 
 Arrow functions are not just a "shorthand" for writing small stuff. They have some very specific and useful features.
 
-JavaScript is full of situations where we need to write a small function, that's executed somewhere else.
+JavaScript is full of situations where we need to write a small function that's executed somewhere else.
 
 For instance: