UPDATED GUIDES: Adafruit MatrixPortal M4 and Protomatter RGB Matrix Library

UPDATED GUIDES on the Adafruit Learning System: Adafruit MatrixPortal M4 and Protomatter RGB Matrix Library

With the release of MatrixPortal M4, there’s a rush of projects using this new LED-matrix-centric development board. The introductory guide’s been updated with explanations of the MatrixPortal (for CircuitPython) and Adafruit_Protomatter (for Arduino) libraries. The latter guide and example code have been refreshed to better explain their use for first-timers.