Document pinout in README

[redfast00]

No description provided.

[lurch]

This repo is for the debugprobe software, which can run on a Debug Probe, or a Pico, or an any number of other RP2040-based boards.
Documentation for the Debug Probe hardware (note the different capitalisation) can be found at https://www.raspberrypi.com/documentation/microcontrollers/debug-probe.html

[redfast00]

In the releases of this repo, there is firmware for the Pico (debugprobe_on_pico.uf2); it could be useful to document what functions are on what pins of the Pi Pico. Now I had to dig through the source code (just to find that the reset pin functionality is not enabled by default, so I have to recompile anyways).

[redfast00]

(This issue is more as a way to remind myself to create a PR)

[lurch]

See Appendix A of https://datasheets.raspberrypi.com/pico/getting-started-with-pico.pdf

[fduxiao]

Hi @redfast00, I think the best way is not to document pinout in README, because you may change the pinout when compiling the binary. I think it's better to add pinout to binary info. You can read pin definition with picotool info debugprobe.uf2 -a. See my pull request #113.