[#6613] Add fileContent in the example and removed sentence

Author: wouterj

components/http_foundation/introduction.rst

@@ -481,17 +481,18 @@ non-ASCII filenames is more involving. The
 :method:`Symfony\\Component\\HttpFoundation\\ResponseHeaderBag::makeDisposition`
 abstracts the hard work behind a simple API::
 
+    use Symfony\Component\HttpFoundation\Response;
     use Symfony\Component\HttpFoundation\ResponseHeaderBag;
 
-    $d = $response->headers->makeDisposition(
+    $fileContent = ...; // the generated file content
+    $response = new Response($fileContent);
+
+    $disposition = $response->headers->makeDisposition(
         ResponseHeaderBag::DISPOSITION_ATTACHMENT,
         'foo.pdf'
     );
 
-    $response->headers->set('Content-Disposition', $d);
-
-Then you must set the file's content as usual, for example by using
-:method:`Symfony\\Component\\HttpFoundation\\Response::setContent`.
+    $response->headers->set('Content-Disposition', $disposition);
 
 Alternatively, if you are serving a static file, you can use a
 :class:`Symfony\\Component\\HttpFoundation\\BinaryFileResponse`::
@@ -513,6 +514,7 @@ if it should::
 With the ``BinaryFileResponse``, you can still set the ``Content-Type`` of the sent file,
 or change its ``Content-Disposition``::
 
+    // ...
     $response->headers->set('Content-Type', 'text/plain');
     $response->setContentDisposition(
         ResponseHeaderBag::DISPOSITION_ATTACHMENT,