Our goal: customize the help message for the root command.

Existing solution won't help, because we need to append the message on top of auto-gen help, and also modify the auto-gen help a little bit.

Context for our cmd app: below is the root cmd, and we have a sub-cmd under the root as well as a git-style-sub-command.

commander
    .description('')
    .command('sub-cmd')
    .command('git-style-sub-cmd')
    .version(require('../package.json').version)
    .option('-h, --help', 'output help message', () => {
        console.log('custom help msg');
    })
    .parse(process.argv);

In the example I tried using option('-h, --help'), the console.log works for me with my demanded help output. But when I try sub-cmd and git-style-sub-cmd, the help message for the root command is always coming along when I type "cmd sub-cmd --help" and "cmd git-style-sub-cmd --help".

I noticed #242 , where @shadowspawn mentioned it won't be supported. Reopen it as it'd be an important feature for us.