Update article.md

Typo - miss closing parenthesis in add.map() example

1-js/05-data-types/05-array-methods/article.md

@@ -316,7 +316,7 @@ The syntax is:
 ```js
 let result = arr.map(function(item, index, array) {
   // returns the new value instead of item
-}
+})
 ```
 
 It calls the function for each element of the array and returns the array of results.