[DOCS] Add Theengs Plug links (#1416)

* [DOCS] Add Theengs Plug links

README.md

@@ -18,6 +18,20 @@ The reference sheet, with the list of all functions, pinouts is [here](https://d
 
 Upload OpenMQTTGateway directly from the [upload page](https://docs.openmqttgateway.com/upload/web-install.html) (no additional software required) or [build your own configuration](https://docs.openmqttgateway.com/upload/builds.html) with [PlatformIO](https://platformio.org/) or [Arduino IDE](https://www.arduino.cc/en/software)
 
+
+## First ready to go OpenMQTTGateway device !
+
+[Theengs plug](https://shop.theengs.io/products/theengs-plug-smart-plug-ble-gateway-and-energy-consumption) is available flashed with OpenMQTTGateway, and brings the functions below:
+* BLE to MQTT gateway, tens of Bluetooth devices supported thanks to Theengs Decoder library. The plug uses an ESP32 acting as a BLE to Wifi gateway to scan, decode and forward the data of the nearby sensors,
+* Smart plug that can be controlled remotely,
+* Energy consumption monitoring,
+* Presence detection (beta).
+
+[![](./docs/img/Theengs-Plug-OpenMQTTGateway.png)](https://shop.theengs.io/products/theengs-plug-smart-plug-ble-gateway-and-energy-consumption)
+
+Support the project by purchasing the [Theengs plug](https://shop.theengs.io/products/theengs-plug-smart-plug-ble-gateway-and-energy-consumption)
+The plug is available in North America only, other regions are planned.
+
 ## Compatible items
 
 * [List of supported devices](https://compatible.openmqttgateway.com/index.php/devices/), door/window sensors, PIR sensors, smoke detectors, weather stations...