drupal/modules/help.module

<?php
// $Id$

function help_link($type) {
  if ($type == "admin") {
    $links[] = "<a href=\"admin.php?mod=help\">help</a>";
  }

  return $links ? $links : array();
}

function help_admin() {
  foreach (module_list() as $name) {
    if (module_hook($name, "help")) {
      print "<h2>". ucfirst($name) ." module</h2>";
      print module_invoke($name, "help");
    }
  }
}

?>