Xiao NRF52840 keychain node

I wanted to see how small I could make a node which included a display and button to control it, so the Xiao NRF kit seemed like the most logical option.

This node is really small, and I'm really happy with how it came out. Unfortunately I didn't get much time with it as the next day someone persuaded me to sell it to them, so I'll have to build another one at some point.

It requires an alpha Meshtastic build which enables I2C on pins 6&7 (link to the dev in the instructions PDF)

All of the parts needed with links are in the instructions PDF.