Update example

README.md

@@ -36,27 +36,28 @@ progress bar is removed once the delivery is complete:
 ```typescript
 import postman, { item } from "postman";
 document.addEventListener("DOMContentLoaded", () => {
-  const progressBar = document.querySelector("progress");
+  const bar = document.querySelector("progress");
   const span = document.querySelector(".percentage");
-  postman(
+  const delivery = postman(
     item.font("Kanit Regular", "url(/fonts/kanit-regular.ttf)"),
     item.script("/js/app.js"),
     item.image("/images/app.png"),
     item.css("/css/app.css"),
     item.progress((percent) => {
-      progressBar.value = percent;
+      bar.value = percent;
       span.innerText = `${percent}%`;
     })
-  ).deliver()
-   .then((package) => {
-      /* Add page assets */
-      package.fonts.forEach((font) => documents.fonts.add(font));
-      package.scripts.forEach((script) => document.body.appendChild(script));
-      package.css.forEach((css) => document.head.appendChild(css));
-      /* Replace progress bar */
-      progressBar.remove();
-      span.remove();
-   });
+  ).deliver();
+
+  delivery.then((package) => {
+    /* Add page assets */
+    package.fonts.forEach((font) => documents.fonts.add(font));
+    package.scripts.forEach((script) => document.body.appendChild(script));
+    package.css.forEach((css) => document.head.appendChild(css));
+    /* Replace progress bar */
+    bar.remove();
+    span.remove();
+  });
 });
 ```