Update 'list.md'

list.md

@@ -5,7 +5,9 @@ These exercises will help you get really good at using lists in Python. You'll p
 
 ---
 
-## Exercise 1: Flatten a Nested List
+## Exercise 1
+
+**Flatten a Nested List**
 
 ### Problem
 
@@ -26,7 +28,9 @@ flatten_list([1, [2, 3], [4, [5, 6], 7]])
 
 ---
 
-## Exercise 2: Group Consecutive Duplicates
+## Exercise 2
+
+**Group Consecutive Duplicates**
 
 ### Problem
 
@@ -47,7 +51,9 @@ group_consecutive([1, 1, 2, 2, 2, 3, 1, 1])
 
 ---
 
-## Exercise 3: Rotate List k Times
+## Exercise 3
+
+**Rotate List k Times**
 
 ### Problem
 
@@ -68,7 +74,9 @@ rotate_list([1, 2, 3, 4, 5], 2)
 
 ---
 
-## Exercise 4: List Difference by Value and Order
+## Exercise 4
+
+**List Difference by Value and Order**
 
 ### Problem