Update Service Principal instructions for 6.0.0

Author: Stephen Tramer

docs-conceptual/azurermps-6.0.0/create-azure-service-principal-azureps.md

@@ -74,7 +74,8 @@ The `New-AzureRmADServicePrincipal` cmdlet is used to create the service princip
 ```powershell
 Add-Type -Assembly System.Web
 $password = [System.Web.Security.Membership]::GeneratePassword(16,3)
-New-AzureRmADServicePrincipal -ApplicationId 00c01aaa-1603-49fc-b6df-b78c4e5138b4 -Password $password
+$securePassword = ConvertTo-SecureString -Force -AsPlainText -String $password
+New-AzureRmADServicePrincipal -ApplicationId 00c01aaa-1603-49fc-b6df-b78c4e5138b4 -Password $securePassword
 ```
 
 ```