The command does not tell how does installing the Azure IoT Extensions for CLI helps.

The one-liner earlier was not very clear and did not give a clear picture

Author: neerajks77

articles/iot-hub/iot-hub-arduino-iot-devkit-az3166-get-started.md

@@ -77,7 +77,12 @@ A device must be registered with your IoT hub before it can connect. In this qui
     ```
 
    > [!NOTE]
-   > If you get an error running `device-identity`, install the [Azure IOT Extension for Azure CLI](https://github.com/Azure/azure-iot-cli-extension/blob/dev/README.md) for more details.
+   > If you get an error running `device-identity`, install the [Azure IOT Extension for Azure CLI](https://github.com/Azure/azure-iot-cli-extension/blob/dev/README.md).
+   > Run the following command to add the Microsoft Azure IoT Extension for Azure CLI to your Cloud Shell instance. The IOT Extension adds IoT Hub, IoT Edge, and IoT Device Provisioning Service (DPS) specific commands to Azure CLI
+   
+    ```azurecli-interactive
+    az extension add --name azure-iot
+    ```
   
 1. Run the following commands in Azure Cloud Shell to get the _device connection string_ for the device you just registered: