code: public AppHelper add(String name, String description)
      {
          add(name, null, description, null);
          return this;
      }
docs: Adds an argument to this application helper.
  
  @param name the (case-sensitive) argument name.
  @param description the description for the argument to be displayed in the usage print-out.
  @return reference to this application helper, allowing command-chaining.