minor symfony#13910 🎨 Improved consistency in Upload Files snippet (skmedix)

This PR was merged into the 3.4 branch.

Discussion
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🎨 Improved consistency in Upload Files snippet

Commits
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c2c7dae 🎨 Improved consistency

Author: javiereguiluz

controller/upload_file.rst

@@ -319,7 +319,7 @@ Now you're ready to use this service in the controller::
 
         if ($form->isSubmitted() && $form->isValid()) {
             /** @var UploadedFile $brochureFile */
-            $brochureFile = $form['brochure']->getData();
+            $brochureFile = $form->get('brochure')->getData();
             if ($brochureFile) {
                 $brochureFileName = $fileUploader->upload($brochureFile);
                 $product->setBrochureFilename($brochureFileName);