qmk_firmware/docs/ChangeLog/20190830/PR6245.md

• Update repo to use LUFA as a git submodule
  • /lib/LUFA removed from the repo
  • LUFA set as a submodule, pointing to qmk/lufa
  • This should allow more flexibility with LUFA, and allow us to keep the sub-module up to date, a lot more easily. It was ~2 years out of date with no easy path to fix that. This prevents that from being an issue in the future