Add Portuguese to the main language dropdown (#872)

Author: vitorarjol

themes/vue/layout/partials/language_dropdown.ejs

@@ -5,5 +5,6 @@
     <li><a href="https://jp.vuejs.org/" class="nav-link" target="_blank">日本語</a></li>
     <li><a href="https://ru.vuejs.org/" class="nav-link" target="_blank">Русский</a></li>
     <li><a href="https://kr.vuejs.org/" class="nav-link" target="_blank">한국어</a></li>
+    <li><a href="https://br.vuejs.org/" class="nav-link" target="_blank">Português</a></li>
   </ul>
 </li>