Update M01-Unit 4 Design and implement a Virtual Network in Azure.md

Author: staleycyn

Instructions/Exercises/M01-Unit 4 Design and implement a Virtual Network in Azure.md

@@ -12,7 +12,7 @@ Now you're ready to deploy virtual networks in the Azure portal.
 
 Consider the fictional organization Contoso Ltd, which is in the process of migrating infrastructure and applications to Azure. In your role as network engineer, you must plan and implement three virtual networks and subnets to support resources in those virtual networks.
 
-### Estimated time: 20 minutes
+## Estimated time: 20 minutes
 
 The **CoreServicesVnet** virtual network is deployed in the **East US** region. This virtual network will have the largest number of resources. It will have connectivity to on-premises networks through a VPN connection. This network will have web services, databases, and other systems that are key to the operations of the business. Shared services, such as domain controllers and DNS also will be located here. A large amount of growth is anticipated, so a large address space is necessary for this virtual network.