Usage for command should include parent commands

[mojavelinux]

The usage for an action-based (sub)command is misleading. It seems to suggest that the command can be used by itself, without the parent.

For example, if we were making the git cli with commander.js, the usage for add would look like:

Usage: add [options] <pathspec>

However, it should show the parent command (the context) as well:

Usage: git add [options] <pathspec>

I guess if it's an executable it's fine, so this just applies to subcommands that are not executables.

[privateOmega]

Please merge this.

[shadowspawn]

This issue will be resolved when v3.0.0 is released. Available now as a prerelease. See #1001

[shadowspawn]

Shipped in v3 (thanks @mojavelinux): https://github.com/tj/commander.js/releases/tag/v3.0.0