chore(docs): set Matomo site ID to 21

Author: marc0olo

docs-site/matomo.js

@@ -5,11 +5,11 @@ _paq.push(["trackPageView"]);
 (function () {
   var u = "https://internetcomputer.matomo.cloud/";
   _paq.push(["setTrackerUrl", u + "matomo.php"]);
-  _paq.push(["setSiteId", "CHANGEME"]);
+  _paq.push(["setSiteId", "21"]);
   var d = document,
     g = d.createElement("script"),
     s = d.getElementsByTagName("script")[0];
   g.async = true;
-  g.src = "//cdn.matomo.cloud/internetcomputer.matomo.cloud/matomo.js";
+  g.src = "https://cdn.matomo.cloud/internetcomputer.matomo.cloud/matomo.js";
   s.parentNode.insertBefore(g, s);
 })();