KiCad Instructions

[LimesKey]

Closes #878

Adds instructions for beginners on how to use KiCad

[blazecoding2009]

Looks good! This is gonna help lots of people

[prophetorpheus]

Hi, I'm Orpheus Leap! Here to help you review your PR.

.:

Required files

✅	README.md	A description of your project
❌	cart.png	You need to include a screenshot of your JLCPCB. Check out these instructions. If you already have one, make sure it's a PNG file named exactly "cart.png".

Formatting for multi-board projects not implemented yet.
Happy OnBoarding!
_{This bot is a simpler helper for common submission types. If there's an error with this, please point it out and someone from the OnBoard team will look at it manually.}