Add multi-midi

Author: mcauser

readme.md

@@ -81,6 +81,7 @@ Other places you can look for MicroPython Libraries:
 * [micropython-tas2505](https://github.com/miketeachman/micropython-tas2505) - MicroPython driver for the Texas Instruments TAS2505 Digital Input Class-D Speaker Amplifier.
 * [yx5300](https://github.com/QuirkyCort/IoTy/blob/main/public/extensions/yx5300.py) - MP3 player that can be controlled via a serial interface.
 * [micropython_nonblocking_buzzer](https://github.com/jornamon/micropython_nonblocking_buzzer) - A nonblocking implementation of a buzzer class that allows you to play basic melodies or sound patterns without blocking the main loop while the sound is being played.
+* [multi-midi](https://github.com/HLammers/multi-midi) - Library for RP2 boards, providing an interface for UART and PIO based hardware MIDI and USB MIDI 1.0.
 
 ### Communications