I am learning to create a module. I have created a simple module. The modules successfully appeared in modules list in admin panel. Now I am learning to implement a hook. But the Help link doesn't appear in the admin panel. Following are files I created for module. Please review these codes and help me if there is something wrong there? I am using drupal 7.

customsite.info file code

; $Id$
name = Custom Site functions
description = Custom functions for this site.
core = 7.x

customsite.install file code

?php
// $Id: customsite.install

/**
* Implementation of hook_install()
*/
function customsite_install() {
  // Set the module weight so it can override other modules.
  db_query("UPDATE {system} SET weight = 99 WHERE name = 'customsite'");
}

/**
* Implementation of hook_uninstall()
*/
function customsite_uninstall() {
  // Remove variables which is defined in our module
  variable_del('customsite_setting1');
  variable_del('customsite_setting2');
}

customsite.module file code

<?php
// $Id: customsite.module

/**
* @file
* Custom functions for this site.
*/

function customsite_help($path, $arg) {
  switch ($path) {
    case "admin/help#customsite":
      return '<p>' . t("Displays links to nodes created on this date") . '</p>';
      break;
  }
}