README: add more documentation.
README: add more documentation.

Signed-off-by: Jan Losinski <577c4104c61edf9f052c616c0c23e67bef4a9955@wh2.tu-dresden.de>

puuu/MQTT433gateway,puuu/MQTT433gateway,puuu/MQTT433gateway,puuu/MQTT433gateway,puuu/MQTT433gateway,puuu/MQTT433gateway