Added GeeekPi RP2040 Plus

[pszsh]

It's basically identical to the normal Pico, but it has 4MB RAM and USB C.

https://wiki.52pi.com/index.php?title=EP-0175

[pszsh]

Shit, sorry, I forgot to update the README, may I just submit another pull request after this one to fix that?

[earlephilhower]

You can just add a commit to your branch and re-push, no need for new PR. GH will pick it up automatically

[pszsh]

I apologize, it's been a while since I've made a github contribution. I don't really know what you mean. Do I need to do anything more, or is it going to merge it automatically?

[earlephilhower]

You're good, no worries! It always takes your branch:HEAD, so your README update is now here.

[pszsh]

Aha, yes, I realize what you mean now. Cool cool, it should be good now then.

Thanks for maintaining this REPO, haven't actually made anything yet, but I've been on a mission to build my own audio interface from scratch... so far, I have failed miserably ;D It turns out people were not joking about how difficult it is. I'll figure it out.