"memory region" can be given an address once and then when repeated,
it will try to find a region just beyond the last one it printed.
This continues until the end of the address space.
Then it gives you an error showing the usage, which is odd because
you just saw a bunch of "memory region" with no options work.
So I've improved the error a bit to imply its to do with the repetition.
Then described the repeating behaviour in the help text.
e9ac1a3190