In this book, we used a configuration file for the router. If you come from Symfony, for example, you might want to use annotations. For this, you need to change the router information in the DI:

<?php

use Phalcon\Mvc\Router\Annotations;

$di['router'] = function() {
    $router = new Annotations(false);
    $router->addResource('Articles', '/api/v1/articles');

    return $router;
};

Then you must modify ArticlesController to look like this:

<?php
namespace App\Api\Controllers;

/**
 * @RoutePrefix("/api/v1/articles")
 */
class ArticlesController extends BaseController {
  /**
  * @Get("/")
  */
  public function listAction() {

  }
}

You can read more about the Annotation router at http://docs.phalconphp.com/en/latest/reference/routing.html#annotations-router. If you need/want, you can also develop your own router, implementing Phalcon\Mvc\RouterInterface.