Add advice about using AI for code generation

[patricoferris]

cc: @talex5 and @avsm

This is based on #763. Happy for it to say something different, but thought I would get the ball rolling here.

[talex5]

Thanks - that looks useful!

For licensing, a lot of what Eio is doing is similar to what the OCaml stdlib does. The stdlib has a different license, and the compiler devs have explicitly told us we can't use their code (e.g. #352 (comment)). I suspect that when asking AI to write e.g. Windows C stubs it will just copy this one source.

Using AI as a search feature to find approaches you didn't know about might be useful though. Though in my limited testing, I found it sends you down the wrong path too often to be useful.

[avsm]

LGTM also; we can revise this in the future but good to be conservative now from a licensing perspective.