Update README.rst
Update README.rst

Added pin layouts for ATMEGA32U4-based Arduinos
lpr0lpd/rfid,Rotzbua/rfid,prikevs/rfid,CapeSepias/rfid,sophiekovalevsky/rfid,Rotzbua/rfid,smallkid/rfid,miguelbalboa/rfid,northDacoder/rfid,tamchau2809/rfid,irhastofa/rfid,mangine/mraa_MFRC522,webdevbrian/rfid,r44947/rfid,mirko314/rfid,1upon0/rfid,yaalsn/rfid,juantejedavz/rfid,LaloHao/rfid,hramrach/rfid