Provide dummy example

[georgringer]

what about providing a dummy implementation which can also be referenced in the example of the readme?

something like this would be enough

<?php

declare(strict_types=1);

namespace Sinso\AppRoutes\Example;

use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use Psr\Http\Server\RequestHandlerInterface;
use TYPO3\CMS\Core\Http\JsonResponse;

class Demo implements RequestHandlerInterface
{
    public function handle(ServerRequestInterface $request): ResponseInterface
    {
        $data = ['example' => 42];
        return new JsonResponse($data);
    }

}