Fix htaccess sample to use index.php instead of app.php

Author: chr-hertel

src/Symfony/Component/HttpFoundation/ServerBag.php

@@ -51,7 +51,7 @@ public function getHeaders()
              * RewriteCond %{HTTP:Authorization} .+
              * RewriteRule ^ - [E=HTTP_AUTHORIZATION:%0]
              * RewriteCond %{REQUEST_FILENAME} !-f
-             * RewriteRule ^(.*)$ app.php [QSA,L]
+             * RewriteRule ^(.*)$ index.php [QSA,L]
              */
 
             $authorizationHeader = null;