Update the webpack example to account for outputting of JavaScript modules (PR 17055 follow-up)

*Please note:* While following the steps in the README still works with this patch, in the sense that the example runs and successfully renders a PDF document, I unfortunately cannot tell if it illustrates Webpack best practices.

examples/webpack/main.mjs

@@ -0,0 +1,29 @@
+// Any copyright is dedicated to the Public Domain.
+// http://creativecommons.org/licenses/publicdomain/
+
+// Hello world example for webpack.
+
+import * as pdfjsLib from "pdfjs-dist";
+
+const pdfPath = "../learning/helloworld.pdf";
+
+// Setting worker path to worker bundle.
+pdfjsLib.GlobalWorkerOptions.workerSrc =
+  "../../build/webpack/pdf.worker.bundle.js";
+
+// Loading a document.
+const loadingTask = pdfjsLib.getDocument(pdfPath);
+const pdfDocument = await loadingTask.promise;
+// Request a first page
+const pdfPage = await pdfDocument.getPage(1);
+// Display page on the existing canvas with 100% scale.
+const viewport = pdfPage.getViewport({ scale: 1.0 });
+const canvas = document.getElementById("theCanvas");
+canvas.width = viewport.width;
+canvas.height = viewport.height;
+const ctx = canvas.getContext("2d");
+const renderTask = pdfPage.render({
+  canvasContext: ctx,
+  viewport,
+});
+await renderTask.promise;