minor #100 Update Form example (pierrejoye, weaverryan)

This PR was merged into the main branch.

Discussion
----------

Update Form example

Without specifying the action, Turbo redirect the full page to /.

name="product_new" is not necessary in this specific example, it however may help newcomer to understand they can have separate route for this action (even if not recommended by the Symfony Form docs).

Not sure if it is a bug in turbo or me doing wrong, adding this fixes it.

| Q             | A
| ------------- | ---
| Bug fix?      | yes/no
| New feature?  | yes/no <!-- please update src/**/CHANGELOG.md files -->
| Tickets       | Fix #... <!-- prefix each issue number with "Fix #", no need to create an issue if none exist, explain below instead -->
| License       | MIT

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Commits
-------

3248ee0 Removing warning not needed anymore and minor cs
a3ff4ac Update Form example

Author: weaverryan

src/Turbo/README.md

@@ -97,12 +97,14 @@ automatically:
 
 ```php
 /**
- * @Route("/product/new")
+ * @Route("/product/new", name="product_new")
  */
 public function newProduct(Request $request): Response
 {
     return $this->handleForm(
-        $this->createForm(ProductFormType::class),
+        $this->createForm(ProductFormType::class, null, [
+            'action' => $this->generateUrl('product_new'),
+        ]),
         $request,
         function (FormInterface $form) {
             // save...