Add Google verification tag

In order to tell Google Search that our main site has changed to
dillo-browser.org, we first need to have the GitHub pages site verified,
so we can mark the new site as the canonical URL.

Author: rodarima

index.html

@@ -4,6 +4,7 @@
     <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
     <title>Dillo Website</title>
     <link rel="icon" type="image/png" href="img/favicon.png">
+    <meta name="google-site-verification" content="zUiOCHawxM1jqB0LgnCcOmQzi3iDmu-vLtwPnbqFLWc" />
     <style>
 body {
   background: white;