Document browser module availability in WASM Demo

wasm/demo/src/index.ejs

@@ -67,6 +67,13 @@
             </li>
         </ul>
 
+        <p>
+            Limited Interaction with browser is possible from Python by using
+            the <code>browser</code> module. Browser APIs such as
+            <code>alert()</code>, <code>confirm()</code>, <code>prompt()</code>
+            and <code>fetch()</code> are included in the module.
+        </p>
+
         <a href="https://github.com/RustPython/RustPython">
             <img
                 style="position: absolute; top: 0; right: 0; border: 0;"