Update Az.Network.psd1

Author: Nickcandy

src/Network/Network/Az.Network.psd1

@@ -822,7 +822,7 @@ PrivateData = @{
 * Added support for ''ResiliencyModel'' property in ''New-AzVirtualNetworkGateway'' and ''Set-AzVirtualNetworkGateway'' command for ExpressRoute'
 
         # Prerelease string of this module
-        # Prerelease = ''
+        Prerelease = 'preview'
 
         # Flag to indicate whether the module requires explicit user acceptance for install/update/save
         # RequireLicenseAcceptance = $false