docs(ngValue) Replace input[select] with option for clarity

It is impossible to create an `input[select]`, so it appears the intention
here was actually `option`.

Fixes #7994

While `ngOptions` would probably be easier to use in most cases, someone may have a use case for using `ngValue` with `option` which is why I decided to change it in lieu of deleting it, as had been mentioned in the issue.