(AzureCXP) fixes MicrosoftDocs/azure-docs#48754

Modified a sentence under Best practices section.

Author: SubhashVasarapu-MSFT

articles/virtual-network/virtual-networks-overview.md

@@ -33,7 +33,7 @@ As you build your network in Azure, it is important to keep in mind the followin
 - Ensure non-overlapping address spaces. Make sure your VNet address space (CIDR block) does not overlap with your organization's other network ranges.
 - Your subnets should not cover the entire address space of the VNet. Plan ahead and reserve some address space for the future.
 - It is recommended you have fewer large VNets than multiple small VNets. This will prevent management overhead.
-- Secure your VNet using Network Security Groups (NSGs).
+- Secure your VNet's by assigning Network Security Groups (NSGs) to the subnets beneath them.
 
 ## Communicate with the internet