Grammar fix

Should be "its", not "it's" (which means "it is")

Author: IanWitham

1-js/02-first-steps/12-while-for/5-replace-for-while/task.md

@@ -4,7 +4,7 @@ importance: 5
 
 # Replace "for" with "while"
 
-Rewrite the code changing the `for` loop to `while` without altering it's behavior (the output should stay same).
+Rewrite the code changing the `for` loop to `while` without altering its behavior (the output should stay same).
 
 ```js run
 for (let i = 0; i < 3; i++) {