Update README.md

Author: khoih-prog

README.md

@@ -135,7 +135,7 @@ The catch is **your function is now part of an ISR (Interrupt Service Routine),
 ## Prerequisites
 
 1. [`Arduino IDE 1.8.15+` for Arduino](https://www.arduino.cc/en/Main/Software)
-2. [`Arduino mbed_rp2040 core 2.1.0+`](https://github.com/arduino/ArduinoCore-mbed) for Arduino (Use Arduino Board Manager) RP2040-based boards, such as **Arduino Nano RP2040 Connect, RASPBERRY_PI_PICO, etc.**. [![GitHub release](https://img.shields.io/github/release/arduino/ArduinoCore-mbed.svg)](https://github.com/arduino/ArduinoCore-mbed/releases/latest)
+2. [`Arduino mbed_rp2040 core 2.4.1+`](https://github.com/arduino/ArduinoCore-mbed) for Arduino (Use Arduino Board Manager) RP2040-based boards, such as **Arduino Nano RP2040 Connect, RASPBERRY_PI_PICO, etc.**. [![GitHub release](https://img.shields.io/github/release/arduino/ArduinoCore-mbed.svg)](https://github.com/arduino/ArduinoCore-mbed/releases/latest)
 
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