README: update Teensy++ 2.0 situation as per https://www.pjrc.com/store/teensypp.html

Create pcb_confirmed_working_on_JLCPCB.zip (#23)

Revert "added gerber file for jlcpcb (#20)" (#21) This reverts commit 2b1d9c87fc2a7dc78e976b8463c90cef5bcb5e96.

added gerber file for jlcpcb (#20) Co-authored-by: Sanic

README: collect debugging/troubleshooting info

soldering instructions: link LED data sheet related to https://github.com/kinx-project/kint/issues/13

README: clarify solder instruction regarding vertical pin header related to https://github.com/kinx-project/kint/issues/13

reference kint36 pull request

README: which teensy: add consideration regarding advanced QMK feats

README: link adapter board