Adding PGA2040 as supported.

[zhellsh]

Hello! I was scrolling through here when I noticed the PGA2040 wasn't listed! This board has a significant amount of potential and more can be done with it if Rust was supported on it! It is a fun little board and I do hope that this sparks some amount of interest/want to add support to it! In this case, support would be the examples for beginners!
- Tired

[ithinuel]

Hi Tired 👋

Thank you for the head-up. Boards supports are usually added by people owning one of them as this makes it easier to validate the implementation/configuration. If you have one, feel free to open a PR :)

That being said, I had a quick look at the board and it seems very similar to what the rp-pico does (only without the handy usb connector), so one could probably transparantly use the rp-pico with the PGA2040 and no futher work would be required on a BSP.