public Integer call() throws IOException {
        return generateManPage(config, spec.root());
    }
Invokes {@link #generateManPage(Config, CommandLine.Model.CommandSpec...)} to
generate man pages for all non-hidden commands in the hierarchy from the
top-level command down. This method is only called when this class is used as
a subcommand.

@return an exit code indicating success or failure, as follows:
        <ul>
        <li>0: Successful program execution.</li>
        <li>1: A runtime exception occurred while generating man pages.</li>
        <li>2: Usage error: user input for the command was incorrect, e.g.,
        the wrong number of arguments, a bad flag, a bad syntax in a
        parameter, etc.</li>
        <li>4: A template file exists in the template directory. (Remove the
        `--template-dir` option or use `--force` to overwrite.)</li>
        </ul>
@throws IOException if a problem occurred writing files.
docs/genadoc.java