updated .gitattributes

git attribute update

Update README.md

open-sourced hardware, 3D printed models added. Final version before the trip!

signals

update readme signals.

add instruction audios.

audio added.

smoke and resolve two bugs for xbox controller and for black screen error.

fix game over bug, add tutorial pictures.

three two one go

game over.

add audio files.

score sprite done.

score sprite.