Update ChangeLog for certificate-based authentication feature

Author: brandonv191

src/Network/Network/ChangeLog.md

@@ -19,6 +19,10 @@
 --->
 
 ## Upcoming Release
+* Added certificate-based authentication support for VPN Gateway connections
+    - New cmdlet `New-AzVirtualNetworkGatewayCertificateAuthentication` to create certificate authentication configuration
+    - Added `-AuthenticationType` and `-CertificateAuthentication` parameters to `New-AzVirtualNetworkGatewayConnection` and `Set-AzVirtualNetworkGatewayConnection`
+    - Added `-UserAssignedIdentityId` parameter to `Set-AzVirtualNetworkGateway` for managed identity configuration
 * Returned appgw and agc in waf policy
 * Updated cmdlet `New-AzFirewallPolicyApplicationRule` to use HTTPS as the default protocol when creating a new FQDN Tag application rule.
 * Added `EnableDnstapLogging` parameter to `New-AzFirewall`