update readme

README.md

 
 Small firmware supporting different environmental sensors, as well as different microcontroller platforms.
 
-Supports SHT21, BME280, CCS811, analog moisture sensors, serial or gpio relais.
+Supports SHT21, BME280, CCS811, analog moisture sensors, serial or gpio relais, [SML](https://wiki.volkszaehler.org/software/sml) smart meter readouts.
 
-Runs on ESP32, ESP8266, Arduino Uno Wifi Developer Edition.
+Runs on ESP32, ESP8266, [Arduino Uno Wifi Developer Edition](https://github.com/JAndrassy/UnoWiFiDevEdSerial1), [Heltec Lora32 V3](https://heltec.org/project/wifi-lora-32-v3/), [Cheap-Yellow-Display](https://github.com/witnessmenow/ESP32-Cheap-Yellow-Display).
+
+[![ESP-Env with BME280](https://www.xythobuz.de/img/espenv_10_small.jpg)](https://www.xythobuz.de/img/espenv_10.jpg)
+[![SML LoRa transmitter](https://www.xythobuz.de/img/lora_sml_3_small.jpg)](https://www.xythobuz.de/img/lora_sml_3.jpg)
+
+This is all very much specific to my IoT devices at home.
+But it should be easy enough to customize and use as a starting point for your own experiments.
+
+See [this blog post](https://www.xythobuz.de/espenv.html) for my initial temperature measurement experiments.
+And [this blog post](https://www.xythobuz.de/lora_sml.html) for my LoRa SML smart meter bridge.
+Some more stuff about my setup can be found [here](https://www.xythobuz.de/smarthome.html).
+
+Mostly this is my simple playground with an Arduino platform compatible build system set up, to quickly try out things.