doc: Add gco() to documentation. * doc/interpreter/plot.txi: Add gco() to manual. * scripts/plot/gco.m: Add seealso links to docstring. * scripts/plot/gcbf.m: Re-arrange seealso links. Improve docstring. * scripts/plot/gcbo.m: Rewrite second paragraph of docstring. Add seealso link to gco.

#include <octave/oct.h>

DEFUN_DLD (helloworld, args, nargout,
  "Hello World Help String")
{
  int nargin = args.length ();
  octave_stdout << "Hello World has " << nargin
        << " input arguments and "
        << nargout << " output arguments.\n";
  return octave_value_list ();
}