Add example and notes on using require in renderer process

index.html

@@ -11,4 +11,9 @@
     Chromium <script>document.write(process.versions.chrome)</script>,
     and Electron <script>document.write(process.versions.electron)</script>.
   </body>
+
+  <script>
+    // You can also require other files to run in this process
+    require('renderer.js')
+  </script>
 </html>

renderer.js

@@ -0,0 +1,2 @@
+// This file is required by the index.html file and will
+// be executed in the renderer process for that window.