Add no-referrer-when-downgrade (#360)

Co-authored-by: Andrei Bogdan <[email protected]>

head.html

@@ -1,5 +1,6 @@
+<meta name="referrer" content="no-referrer-when-downgrade" />
 <meta name="viewport" content="width=device-width, initial-scale=1"/>
 <script src="/scripts/lib-franklin.js" type="module"></script>
 <script src="/scripts/utils/utils.js" type="module"></script>
 <script src="/scripts/scripts.js" type="module"></script>
-<link rel="stylesheet" href="/styles/styles.css"/>
+<link rel="stylesheet" href="/styles/styles.css"/>