ftl new go should explain envar usage for platforms

[matt2e]

GOOS and GOARCH should be mentioned in the help text

[alecthomas]

We don't want users to use these actually, we want it to be reflected from the clsuter.

[matt2e]

Is that happening soonish do you think? One of the loose ends with the language plugin stuff is to make sure envars gets passed alongand I think this was the main use case for that

[stuartwdouglas]

AFAIK the main usage of this currently is to run the kube tests locally on a MBP. Once we have #1845 I don't think there will be any real need for the user to know about these.