Improve ability to reference examples out of the book

1. Examples are not numbered ( or named). Difficult to communicate with others.
2. Cannot point to a particular example using hyperlink. Makes it difficult in written communication. Moving examples to [Gist](https://gist.github.com/) and embedding them back in a page looks to be a sane option ? I suppose, this would bring other benefits as well. e.g. people can fork the example gist and do what not.