Merge pull request #334 from detinsley1s/patch-1

Fix typo

Author: ledsun

problems/scope/problem.md

@@ -29,7 +29,7 @@ IIFE, Immediately Invoked Function Expression, is a common pattern for creating
 
 Example:
 ```js
-(function () { // the function expression is surrounded by parenthesis
+(function () { // the function expression is surrounded by parentheses
   // variables defined here
   // can't be accessed outside
 })() // the function is immediately invoked