Added a help note about why it's the password/username hardcoded

Author: javiereguiluz

app/Resources/views/security/login.html.twig

@@ -94,6 +94,8 @@
         $(document).ready(function() {
             var usernameEl = $('#username');
             var passwordEl = $('#password');
+            // in a real application, hardcoding the user/password would be idiotic
+            // but for the demo application it's very convenient to do so
             if (!usernameEl.val() && !passwordEl.val()) {
                 usernameEl.val('anna_admin');
                 passwordEl.val('kitten');