Update readme.md

Added reference to the Embedded C SDK, which was missing on the device SDK list.

readme.md

@@ -12,6 +12,7 @@ Visit http://azure.com/iotdev to learn more about developing applications for Az
 ## Microsoft Azure IoT SDKs
 
 Microsoft Azure IoT SDKs for Azure IoT Hub and Azure IoT Hub Device Provisioning Service:
+- [Azure IoT SDK for Embedded C](https://github.com/Azure/azure-sdk-for-c/tree/master/sdk/docs/iot) is an alternative for **constrained devices** which enables the BYO (bring your own) network approach: IoT developers have the freedom of choice to bring MQTT client, TLS and Socket of their choice to create a device solution
 - [Azure IoT SDK for C](https://github.com/Azure/azure-iot-sdk-c) written in ANSI C (C99) for portability and broad platform compatibility. There are two device client libraries for C, the low-level iothub_ll_client and the iothub_client (threaded).
 - [Azure IoT SDK for Python](https://github.com/Azure/azure-iot-sdk-python)
 - [Azure IoT SDK for Node.js](https://github.com/Azure/azure-iot-sdk-node)