Update exercise instructions for Azure Front Door setup

Added estimated time for the exercise and clarified the task description.

Author: staleycyn

Instructions/Exercises/M05-Unit 6 Create a front door for a highly available web application using the Azure portal.md

@@ -19,15 +19,18 @@ In this exercise, you will set up an Azure Front Door configuration that pools t
 
 ![Network configuration for Azure Front Door.](../media/6-exercise-create-front-door-for-highly-available.png)
 
+
+## Estimated time: 30 minutes
+
 ## Job skills
 
-In this exercise, you will:
+In this exercise, you:
 
 + Task 1: Create two instances of a web app
 + Task 2: Create a Front Door for your application
 + Task 3: View Azure Front Door in action
 
-## Estimated time: 30 minutes
+
 
 ## Task 1: Create two instances of a web app