Update symfony4/knpu/ep4-security/login-form.md

[xidoc]

Update the tutorial The Login Form for Return type declarations.

In fact, a Response declaration type is required.

use Symfony\Component\HttpFoundation\Response;
...
public function login(AuthenticationUtils $authenticationUtils): Response

How to Build a Login Form

[bocharsky-bw]

Does it cause problems for you? I wonder what error do you see in your code if you don't have that Response return type specified?

In theory, we extend AbstractController that does not have login(), so login() is your personal method and should not require Response return type (though agree, the system requires so that a Reponse object to be returned, but that's a different case and you may totally miss it, i.e. do not specify Response as a return type).

Could you explain your problem a bit more and give us a more context, please?