add lesson 8-3: serving different bundles end

Author: nuria-fl

83-serving-different-bundles/index.html

@@ -12,6 +12,10 @@
       href="https://fonts.googleapis.com/css2?family=Open+Sans:wght@400;600;700&display=swap"
       rel="stylesheet"
     />
+    <script
+      nomodule
+      src="https://cdn.jsdelivr.net/npm/intersection-observer-polyfill@0.1.0/index.min.js"
+    ></script>
     <!-- Global site tag (gtag.js) - Google Analytics -->
     <script
       async