Simple serial terminal example to run on Pico

# Pico serial terminal A simple example to allow a Pico to act as a serial terminal into another Raspberry Pi computer. Useful for setting up a Pi when network setup fails for some reason. Should work for Windows, Linux, or Mac host machines. 1. Add `enable_uart=1` to the Raspberry Pi computer `config.txt` and boot it. 2. Connect pins `pico:{1,2,3}` to `pi:{10,8,6}` 3. Connect to Pico using [Thonny][thonny] 4. From Thonny, run `terminal.py` on Pico, then power up the Pi [thonny]: https://thonny.org/ You should now have a serial terminal to your Raspberry Pi computer through your Pico. ### Errata / Bugs * Input is only taken a whole line at a time after the EOL character. * Line input is ALWAYS echoed back to the terminal as a new line, even passwords * Control characters are dropped so no curses tools (like `raspi-config`) work