Fixing URL for symfony-middleware title

Author: moufmouf

source/middlewares.html

@@ -270,7 +270,7 @@ <h3>
         </div>
         <div class="span6">
             <h3>
-                <a href="https://github.com/thecodingmachine/whoops-stackphp">Symfony 2 middleware</a>
+                <a href="https://github.com/thecodingmachine/symfony-middleware">Symfony 2 middleware</a>
             </h3>
             <p class="by">
                 by moufmouf