Add submission # 5254

#5254

Author: ArduinoBot

registry.txt

@@ -7512,3 +7512,4 @@ https://github.com/guerratron/TouchCal.git|Contributed|TouchCal
 https://github.com/GabyGold67/ButtonToSwitch_AVR.git|Contributed|ButtonToSwitch
 https://github.com/MINDS-i/MINDS-i-Utils.git|Contributed|MINDS-i-Utils
 https://github.com/bitbank2/bb_epaper.git|Contributed|bb_epaper
+https://github.com/Kei0208/RX8900.git|Contributed|RX8900