be a little more helpful when board/arch not detected
be a little more helpful when board/arch not detected

I eventually figured out what to do by reading the README (imagine!),
but error messages such as I've proposed here would have made it even
easier to resolve my problem.

But wow, apart from this hiccup with what is perhaps an older Hail, this
was a very lovely board-programming experience!

(I'll post an issue over on tock about how I am sad about having to hack
Makefiles to include "--arch cortex-m4" to make programming work there.)

helena-project/tockloader