added support to use as a PWA

stats.html

@@ -3,6 +3,11 @@
         <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
         <meta name="viewport" content="width=device-width, initial-scale=1">
         <link rel="manifest" href="/manifest.json">
+        <script type="module">
+           import 'https://cdn.jsdelivr.net/npm/@pwabuilder/pwaupdate';
+           const el = document.createElement('pwa-update');
+           document.body.appendChild(el);
+        </script>
         <title>Generator Status...</title>
         <style>
             * {