Drupal 8, OAuth sample hook_menu

oauth.module

<?php

function oauth_menu() {

//...

  $menu['admin/config/services/oauth'] = array(
    'title' => 'OAuth',
    'description' => 'Settings for OAuth',
    'route_name' => 'oauth_admin_form',
    'type' => MENU_NORMAL_ITEM,
  );

//...
}