Update "naughty-from.sh" to account for Windows "latest" images not existing

[tianon]

https://techcommunity.microsoft.com/t5/Containers/Removing-the-latest-Tag-An-Update-on-MCR/ba-p/393045

$ ./naughty-from.sh golang
$ 

$ ./naughty-from.sh nats
 - nats:1.4.1-nanoserver (FROM microsoft/nanoserver:latest) [windows-amd64]
 - nats:1.4.1-windowsservercore (FROM microsoft/windowsservercore:latest) [windows-amd64]
$ 

[tianon]

Pulled in part of fa01936 from #5929 so we get a better message:

$ ./naughty-from.sh nats
 - nats:1.4.1-nanoserver (FROM microsoft/nanoserver:latest) -- completely unsupported base!
 - nats:1.4.1-windowsservercore (FROM microsoft/windowsservercore:latest) -- completely unsupported base!