Fix browserify example and add an exampe

I was confused about how to make the example work because I do not have much experience with Browserify and Gobble, so I would have liked a little example here since Browserify is the main thing I need to get working with Gobble. (Really liking Gobble so far, nice job Rich.)

I also added a little note about running "gobble" instead of "gobble build dist" during debugging since I didn't realize that "gobble build" will swallow the error messages returned by browserify. If you want to reword it, let me know and I can submit a new PR.