[Jinja2] lang btn and cleanup

site/deconference.html

@@ -28,7 +28,7 @@
         <img src="/img/logo-light.svg" alt="Logo" /> Decentrala
       </a>
       <button id="theme-switcher"></button>
-      <a class="lang" hreflang="sr" href="/en/deconference">SR</a>
+      <a class="lang" hreflang="en" href="/en/index">EN</a>
     </header>
     <main>