title: Is there a way to make clap override the [ -h | --help ] flags help text?
body: <p>I'm following the sample code from Rust Clap Package's docs but can't find any reference regarding help text for auto-generated flags [-h and --help].</p>
  
  <pre><code>extern crate clap;
  
  use clap::{App, Arg, SubCommand};
  
  fn main() {
      let matches = App::new("Command One")
          .version("1.0")
          .author("Some Author &lt;the_account@provider.com&gt;")
          .about("Descripción del comando.")
          .arg(Arg::with_name("config")
              .short("c")
              .long("config")
              .value_name("FILE")
              .help("Sets a custom config file")
              .takes_value(true))
          .arg(Arg::with_name("INPUT")
              .help("Sets the input file to use")
              .required(true)
              .index(1))
          .arg(Arg::with_name("v")
              .short("v")
              .multiple(true)
              .help("Sets the level of verbosity"))
  
          // *** I'm trying this ***
          .arg(Arg::with_name("help")
              .short("h")
              .long("help")
              .help("A new help text."))
          // ***********
  
          .subcommand(SubCommand::with_name("test")
              .about("controls testing features")
              .version("1.3")
              .author("Someone E. &lt;someone_else@other.com&gt;")
              .arg(Arg::with_name("debug")
                  .short("d")
                  .help("print debug information verbosely")))
          .get_matches();
  
      let config = matches.value_of("config").unwrap_or("default.conf");
      println!("Value for config: {}", config);
  
      println!("Using input file: {}", matches.value_of("INPUT").unwrap());
  
      match matches.occurrences_of("v") {
          0 =&gt; println!("No verbose info"),
          1 =&gt; println!("Some verbose info"),
          2 =&gt; println!("Tons of verbose info"),
          3 | _ =&gt; println!("Don't be crazy"),
      }
  
      if let Some(matches) = matches.subcommand_matches("test") {
          if matches.is_present("debug") {
              println!("Printing debug info...");
          } else {
              println!("Printing normally...");
          }
      }
  }
  </code></pre>