Clarify target path functionality

security/form_login_setup.rst

@@ -373,4 +373,67 @@ deal with this low level session variable. However, the
 :class:`Symfony\\Component\\Security\\Http\\Util\\TargetPathTrait` utility
 can be used to read (like in the example above) or set this value manually.
 
+When the user tries to access a restricted page, it is redirected to the login page. 
+At that point target path is set and after a successful login, the user will
+be redirected to the target path set before.
+
+To set it on certain public routes, you can create an Event Subscriber:
+
+.. code-block:: php
+    namespace App\EventSubscriber;
+
+    use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+    use Symfony\Component\HttpFoundation\Session\SessionInterface;
+    use Symfony\Component\HttpKernel\Event\GetResponseEvent;
+    use Symfony\Component\HttpKernel\KernelEvents;
+    use Symfony\Component\Security\Http\Util\TargetPathTrait;
+
+    class RequestSubscriber implements EventSubscriberInterface
+    {
+        use TargetPathTrait;
+
+        /** @var SessionInterface */
+        private $session;
+
+        public function __construct(SessionInterface $session)
+        {
+            $this->session = $session;
+        }
+
+        /**
+         * Save targetPath for public routes
+         *
+         * @param GetResponseEvent $event
+         */
+        public function onKernelRequest(GetResponseEvent $event): void
+        {
+            $request = $event->getRequest();
+
+            if (!$event->isMasterRequest()) {
+                return;
+            }
+
+            if ($request->isXmlHttpRequest()) {
+                return;
+            }
+
+            $includedRoutes = ['some-public-route', 'another-route'];
+
+            if (!\in_array($request->attributes->get('_route'), $includedRoutes, true)) {
+                return;
+            }
+
+            $this->saveTargetPath($this->session, 'main', $request->getUri());
+        }
+
+        public static function getSubscribedEvents()
+        {
+            return [
+                KernelEvents::REQUEST => ['onKernelRequest']
+            ];
+        }
+    }
+
+This subscriber will save the target path for the *main* firewall for the `$includedRoutes`. If a user visits `some-public-route`, after a successful login, it will be redirected to that route.
+
 .. _`MakerBundle`: https://symfony.com/doc/current/bundles/SymfonyMakerBundle/index.html