Issue #3063155 by alonaoneill, Willtg: Hook Help is missing

<?php

use Drupal\Core\Routing\RouteMatchInterface;

/**

 * @file

  return $theme;

}

/**

 * Implements hook_help().

 */

function mailer_help($route_name, RouteMatchInterface $arg) {

  switch ($route_name) {

    case 'help.page.mailer':

      $output = '';

      $output .= '<h3>' . t('About') . '</h3>';

      $output .= '<p>' . t('This module provides a new plugin type to define coded emails throughout your website.

        This is a developer module, the provided UI is minimal.') . '</p>';

      $output .= '<h3>' . t('Usage') . '</h3>';

      $output .= '<ul>';

      $output .= '<li>' . t('When creating a site that sends a lot of mails your code gets sloppy fast.') . '</li>';

      $output .= '<li>' . t('Each mail needs a hook_email, hook_template, a calling function, ...') . '</li>';

      $output .= '<li>' . t('This module makes it possible to bundle all the mail data into a single mailer plugin and call the plugin from everywhere on your website.') . '</li>';

      $output .= '</ul>';

      $output .= t('Visit the <a href=":project_link">Mailer project pages</a> on Drupal.org for more information.',[

        ':project_link' => 'https://www.drupal.org/project/mailer'

        ]);

      $output .= '</p>';

      return $output;

  }

}