Add InteractiveAuthenticatorInterface reference

Author: Florian-B

security/custom_authenticator.rst

@@ -176,6 +176,13 @@ can define what happens in these cases:
     above. Use :class:`Symfony\\Component\\Security\\Core\\Exception\\CustomUserMessageAuthenticationException`
     if you want to set custom error messages.
 
+.. tip::
+
+    If your login method is interactive, which means that the user actively logged into your application, you may want your authenticator to implement the 
+    :class:`Symfony\\Component\\Security\\Http\\Authenticator\\InteractiveAuthenticatorInterface`
+    so that it dispatches an 
+    :class:`Symfony\\Component\\Security\\Http\\Event\\InteractiveLoginEvent`
+
 .. _security-passport:
 
 Security Passports