+ jsDelivr CDN info

Thanks to libgrabber, every time a [new release is posted](https://github.com/components/handlebars.js/releases), jsDelivr will find it & automatically upload it.  If you change your file structure, please updated the [include section](https://github.com/jsdelivr/jsdelivr/blob/master/files/handlebarsjs/update.json) or ask us to do it.

I was going to link CDNJS, but they [haven't uploaded to v2.0.0](http://cdnjs.com/libraries/handlebars.js).  Nothing against those cats; we [use their network](http://www.jsdelivr.com/network.php).