Fixed wrong doc, claiming to show show.gsp on action list

Fixed wrong doc, claiming to show show.gsp on action list 
This time in 2.0.x branch.

See: 
http://grails.org/doc/2.2.1/guide/single.html#modelsAndViews
### Selecting the View

In both of the previous two examples there was no code that specified which view to render. So how does Grails know which one to pick? The answer lies in the conventions. Grails will look for a view at the location grails-app/views/book/show.gsp for this list action:

```class BookController {
    def show() {
         [book: Book.get(params.id)]
    }
}```