Prototype v3

• Use keyboard matrix, put hat switch to same board as other thumb plate switches, fixes to instructions, add circuit board design and part list
• Updated thumb side circuit board design
• Added 2 buttons

What's Changed

• Prototype v3 by @tloimu in #3

New Contributors

• @tloimu made their first contribution in #3

Full Changelog: v1.0-alpha.2...v1.0-alpha.3