Enhance example in Day 5 - Lists by adding output comment to list1.extend() in 30 Days of Python challenge

Persain/05_lists.md

@@ -416,7 +416,7 @@ print(fruits_and_vegetables ) # ['banana', 'orange', 'mango', 'lemon', 'Tomato',
 # سینتکس
 list1 = ['item1', 'item2']
 list2 = ['item3', 'item4', 'item5']
-list1.extend(list2)
+list1.extend(list2) # ['item1', 'item2', 'item3', 'item4', 'item5']
 ```
 
 ```py