jfu-1.0.x-dev/modules/jfu_usage/jfu_usage.module

<?php

use \Drupal\Core\Routing\RouteMatchInterface;

/**
 * Implements hook_help().
 */
function jfu_usage_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    case 'help.page.jfu_usage':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('Provides pages where you can find out the contents where the components are used.') . '</p>';
      return $output;

    default:
  }
}