added includemod example for javascript

accordingly to "http://vertx.io/mods_manual.html#including-the-resources-of-modules"

- [ ] open a PR to fit and link this example at https://github.com/vert-x/vert-x.github.io/blob/master/mods_manual.html#L310 (corresponding issue: https://github.com/vert-x/vert-x.github.io/issues/13)