Update documentation ecommerce modals popups

Author: Martussky

en/tools/ecommerce/docs/design-blocks/modals/o-ss.html

@@ -1,6 +1,7 @@
 <li class="nav-item"><a class="nav-link active" href="#introduction">Introduction</a></li>
 <li class="nav-item"><a class="nav-link" href="#modal-login">Login</a></li>
 <li class="nav-item"><a class="nav-link" href="#modal-register">Register</a></li>
+<li class="nav-item"><a class="nav-link" href="#modal-login-register">Login / Register</a></li>
 <li class="nav-item"><a class="nav-link" href="#modal-newsletter">Newsletter</a></li>
 <li class="nav-item"><a class="nav-link" href="#modal-contact">Contact</a></li>
 <li class="nav-item"><a class="nav-link" href="#modal-cookies">Cookies</a></li>