extension.json

{
    "apiVersion": "2018-06-01",
    "type": "Microsoft.Compute/virtualMachines/extensions",
    "name": "[concat(parameters('VM_Name'),'/config-server')]",
    "location": "[resourceGroup().location]",
    "dependsOn": [
        "[concat('Microsoft.Compute/virtualMachines/', parameters('VM_Name'))]"
    ],
    "tags": {
        "displayName": "config-server"
    },
    "properties": {
        "publisher": "Microsoft.Compute",
        "type": "CustomScriptExtension",
        "typeHandlerVersion": "1.9",
        "autoUpgradeMinorVersion": true,
        "settings": {
            "fileUris": [
                "https://raw.githubusercontent.com/wvanbesien/regionalSettings/master/SetLanguage.ps1"
            ]
        },
        "protectedSettings": {
            "commandToExecute": "powershell -ExecutionPolicy Unrestricted -File setlanguage.ps1 -lng en-AU"
        }
    }
}