comment about collection

Author: dominikzogg

doc/Migration/5.x-6.x.md

@@ -8,3 +8,5 @@ This makes the framework as bit less flexible for special use cases, but easier
 Resulting changes:
 - `Chubbyphp\Framework\Handler\RouteRequestHandler::__construct` does not take a `Chubbyphp\Framework\Middleware\MiddlewareDispatcherInterface` as argument anymore.
 - `Chubbyphp\Framework\Application::__construct` does not take a `Chubbyphp\Framework\Middleware\MiddlewareDispatcherInterface` as argument anymore.
+
+`Chubbyphp\Framework\Collection` is gone, use phpstan if you want to make sure you providing the correct types on array of.