docs: extend naked-objects README (#2362)

[HeVictor]

Extends the naked-objects README to describe the pattern and its uses in more detail.

Special note is that I propose using a Quick start heading to provide the link to the Apache Isis starter app instead of Real world examples as I think it's clearer to show that this is where readers can go and see how this pattern really works, as it is unique from the other patterns because it needs a framework implementation of the pattern itself before one can interact with it.