Started adding basic instructions into the docs.

Hi,

I admired the new Spock documentation but it lacks the basic info that is often needed when one isn't quite a Spock ninja yet :)

I took a shot at adding the basics: mostly this stuff is copied from the Google Code basic tutorial with a bit of editing. I also added a paragraph and a very simple code sample right at the beginning to make it easier for newcomers to follow the text. In fact all of the edits were meant to make the text more approachable.

If you think I'm on a good track I can complete the rest of the sections and of course I would be glad to accept any suggestions and/or objections.