drupalcampbristol/core/modules/migrate/migrate.module

<?php

/**
 * @file
 * Provides the Migrate API.
 */

use Drupal\Core\Routing\RouteMatchInterface;

/**
 * Implements hook_help().
 */
function migrate_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    case 'help.page.migrate':
      $output = '<h3>' . t('About') . '</h3>';
      $output .= '<p>';
      $output .= t('The Migrate module provides a framework for migrating data, usually from an external source into your site. It does not provide a user interface. For more information, see the <a href=":migrate">online documentation for the Migrate module</a>.', array(':migrate' => 'https://www.drupal.org/documentation/modules/migrate'));
      $output .= '</p>';
      return $output;
  }
}