added link for token backup

imaginaerraum_door_admin/templates/tokens.html

@@ -39,4 +39,7 @@
     </tr>
 {% endfor %}
 </table>
+<form action="{{ url_for('backup_tokens') }}" method="get">
+    <input type="submit" value="Token Daten sichern">
+</form>
 {% endblock %}