Windows support? Docs & tests for WSL2

[jayvdb]

It would be great to have core support for windows, assuming it has git bash or similar, with Appveyor CI keeping it from breaking.

[abhishalya]

I would like to work on this issue :)

[jthegedus]

I know this will not help with CI tools, but just so it is documented in this thread for those who are looking for personal Windows use. I've used asdf-vm inside Windows 10 via WSL (Ubuntu) many times over the past two years. Following the Ubuntu Bash setup is compatible with using WSL.