Added sign out

signout.php

@@ -0,0 +1,4 @@
+<?php
+    session_start();
+    session_destroy();
+    header('Location: signin.php');

templates/home.html.twig

@@ -7,6 +7,7 @@
         <h1>Hello {{session.user}}</h1>
         <ul>
             <li><a href="formpasswd.php">Change password</a></li>
+            <li><a href="signout.php">Sign out</a></li>
         </ul>
     </body>
 </html>