Updated PowerShell script for creating vnet and enabling DDoS

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cc: @AbdullahBell

Author: AbdullahBell

articles/ddos-protection/manage-ddos-protection-powershell.md

@@ -57,7 +57,7 @@ You can enable DDoS protection when creating a virtual network. In this example,
 $ddosProtectionPlanID = Get-AzDdosProtectionPlan -ResourceGroupName MyResourceGroup -Name MyDdosProtectionPlan
 
 #Creates the virtual network
-New-AzVirtualNetwork -Name MyVnet -ResourceGroupName MyResourceGroup -Location "East US" -AddressPrefix 10.0.0.0/16 -DdosProtectionPlan $ddosProtectionPlanID -EnableDdosProtection  
+New-AzVirtualNetwork -Name MyVnet -ResourceGroupName MyResourceGroup -Location "East US" -AddressPrefix 10.0.0.0/16 -DdosProtectionPlan $ddosProtectionPlanID.Id -EnableDdosProtection  
 ```
 
 ### Enable DDoS for an existing virtual network