added dockerfile and updated Readme

sw.js

@@ -1,11 +1,19 @@
 // Updated service worker code - sw.js
-const CACHE_NAME = 'chess-timer-cache-v1';
+const CACHE_NAME = 'timer-cache-v1';
 const urlsToCache = [
   '/',
   '/index.html',
   '/styles.css',
-  '/script.js'
-  // Only include files that you're sure exist
+  '/apps.js',
+  '/audio.js',
+  '/icons/android-chrome-192x192.png',
+  '/icons/android-chrome-512x512.png',
+  '/icons/apple-touch-icon.png',
+  '/icons/favicon-32x32.png',
+  '/icons/favicon-16x16.png',
+  '/favicon.ico',
+  '/manifest.json',
+  '/site.webmanifest'
 ];
 
 self.addEventListener('install', event => {