Except this one-sentence rule on Wikipedia, no, I have nothing. Miai-go is really a terrible name since, like I said, miai is a technical term in Go. So searching for "miai go" or "miai-go" is only giving pointers about the definition of this term.
I found this rule under the name "Choice Go" here: https://senseis.xmp.net/?ChoiceGo
I found this rule under the name "Choice Go" here: https://senseis.xmp.net/?ChoiceGo