Add a pointer to "hg -v help" to the bottom of hg help {,cmd} output
This should make it easier to discover global options.
As a bonus, they are no longer displayed by something like a
hg -v help dates
abort: Failed to parse .../t/.hg/hgrcFile contains no section headers.file: .../t/.hg/hgrc, line: 1'invalid\n'