[example] Show how to update page title in controllers

To answer a frequently asked question.

Show how to set static page titles, that don't depend on data, and dynamic page titles, which depend on the data that has just been fetched.

For initial pageload, embed page title in layout file using `<title>{{appData.title}}</title>`.

On subsequent pushState navigations, the `AppView` listens to changes of the `App`'s `title` property and updates `document.title`.