Marlin 2.1.1

[demonlibra]

https://github.com/MarlinFirmware/Marli ... /tag/2.1.1

Marlin 2.1.1 is a bugfix release recommended for all users of Marlin 2.1.
This is a particularly important update for users of Linear Advance and Trinamic stepper drivers, fixing timing issues that could cause shutdown or lost steps under certain conditions. Otherwise, motion handling has been improved and optimized overall.