Also, update the package documentation. The concerns about the global
registry aren't really valid anymore because promauto now also works
with custom registries.
The musings about the http.DefaultMux are more a digression and
shouldn't be in a doc comment.
Signed-off-by: beorn7 <beorn@grafana.com>
Finally, I found an easy solution to provide the "evil"
auto-registration without getting death threats from the wardens of Go
purity. The reasoning can be found in the package's doc comment.
Tom Wilkie