update PIO registry link

Author: matth-x

README.md

@@ -51,7 +51,7 @@ In practical setups, the execution time is largely determined by IO delays and t
 
 ## Developers guide
 
-PlatformIO package: [ArduinoOcpp](https://platformio.org/lib/show/11975/ArduinoOcpp)
+PlatformIO package: [MicroOcpp](https://registry.platformio.org/libraries/matth-x/MicroOcpp)
 
 MicroOcpp is an implementation of the OCPP communication behavior. It automatically initiates the corresponding OCPP operations once the hardware status changes or the RFID input is updated with a new value. Conversely it processes new data from the server, stores it locally and updates the hardware controls when applicable.