reserve -h for --help

[Fil]

As I was looking at the options, I think I'd like us to reserve the -h shorthand for --help (and -v for --version). if we want to keep it short, we could follow live-server and use --host instead of --hostname, maybe?

EDIT: -h is an option for a subcommand, and we can still support observable -h to mean help (though that might be confusing?)

[Fil]

version was added in d8c36a0 by @wiltsecarpenter

[mbostock]

Perhaps we should consider observable help.