add sw script

index.html

@@ -40,3 +40,11 @@
     </main>
 
 </body>
+    <script>
+        if('serviceWorker' in navigator) {
+            window.addEventListener('load', function() {
+                navigator.serviceWorker.register('/sw.js?v=1.5');
+            });
+        }
+    </script>
+</html>