Added a folder for exercises

09_Day_Higher_order_functions/09_day_higher_order_functions.md

@@ -212,7 +212,7 @@ console.log(sum)
 ```js
 let sum = 0;
 const numbers = [1,2,3,4,5];
-numbers.forEach(num => sum += num))
+numbers.forEach(num => sum += num)
 
 console.log(sum)
 ```