feat: allows distinguishing between short and long help with subcommands in the same manner as args
feat: allows distinguishing between short and long help with subcommands in the same manner as args

One can use `App::about` for `-h` short help messsages or
`App::long_about` for `--help` long help messages.

clap-rs/clap,kbknapp/clap-rs,clap-rs/clap,clap-rs/clap,kbknapp/clap-rs