DOCS: FAQ should answer questions, not just give more info

[PeterNerlich]

Docs request

This concerns docs/FAQ.md.

Current behavior

"Arduino Nano/Uno/Mega is not detected" explains the context why this situation might occur.

Expected behavior

"[What to do when] Arduino Nano/Uno/Mega is not detected?" should not only explain where this situation might stem from, but give directions what to do in order to still work with the device.

I imagine this would probably be

• how to figure out what exact model you have and what FQBN string that corresponds to
• how to use the device while explicitly telling arduino-cli what FQBN it is

Additional notes

If I were to be even more nitpicky, "Additional assistance" should probably be "Where to get additional assistance".