Change example in "Page Creation"

[wouterj]

As you can see in #3572, the "Page Creation" docs is a bit confusing.

The problem is that the AcmeDemoBundle has a "hello world demo" using the URL /demo/hello/World. That article is creating exactly the same controller bound to /hello/World.

We should consider changing the example in the page creation docs to another docs, which isn't included in the AcmeDemoBundle.

[weaverryan]

Fixed!