Update azure-virtual-network-limits.md

Add clarification that the limit of NSG address prefixes applies separately to source and destination.

Author: shiniizuka

includes/azure-virtual-network-limits.md

@@ -34,7 +34,7 @@ The following limits apply only for networking resources managed through **Azure
 | Network interface cards |65,536 |
 | Network Security Groups |5,000 |
 | NSG rules per NSG |1,000 |
-| IP addresses and ranges specified for source or destination in a security group |4,000 |
+| IP addresses and ranges specified for source or destination in a security group (The limit applies separately to source and destination) |4,000 |
 | Application security groups |3,000 |
 | Application security groups per IP configuration, per NIC | 20 |
 | Application security groups referenced as source/destination per NSG rule | 10 |