stdlib: Fix argparse:format_help for sub-commands

[jasewo]

When running this script:

#!/usr/bin/env escript

main(Args) ->
    argparse:run(Args, cli(), #{progname => cmd}).

cli() ->
    #{  
        commands => #{
            "sub-1" => #{
                commands => #{
                    "sub-1-1" => #{
                        arguments => [#{name => arg}],
                        help => "Help of sub-1-1 command"
                    }
                },
                help => "Help of sub-1 command"
            }
        },
        help => "Help of main command"
    }.

with these commands:

• ./cmd
• ./cmd sub-1
• ./cmd sub-1 sub-1-1

after Usage section I'm always getting:

Help of main command

like:

$ ./cmd sub-1
error: cmd sub-1: subcommand expected
Usage:
  cmd sub-1 {sub-1-1}

Help of main command

Subcommands:
  sub-1-1 Help of sub-1-1 command

This commit fixes that so sub-commands help is used when possible, like:

$ ./cmd sub-1                                                                                                                                                                                
error: cmd sub-1: subcommand expected                                                                                                                                                        
Usage:                                                                                                                                                                                       
  cmd sub-1 {sub-1-1}                                                                                                                                                                        
                                                                                                                                                                                             
Help of sub-1 command                          

Subcommands:                                   
  sub-1-1 Help of sub-1-1 command              

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CT Test Results

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[max-au]

Good catch. It's pretty rare to have sub-sub commands, and I missed that it prints the generic help instead.

[garazdawi]

Thanks!

[jasewo]

Thank you!