Improve docs

[martinsumner]

Read through. Hopefully just tweaks needed. Perhaps some diagrams?

[jadeallenx]

It's not clear currently if this design is totally decoupled from Riak and could be used by other systems with a need to maintain state across nodes or if it piggy backs on some Riak vnode features and therefore is not a stand alone thing.

[martinsumner]

You're right, it isn't clear. I've added a paragraph to the top of the readme to help.

It is decoupled, but I guess I'm not expecting it to be used outside of Riak. The main reason for decoupling was juts to make testing easier (without needing to integrate with Riak).

[jadeallenx]

I've had a handful of work projects where an independent anti-entropy library would've been enormously helpful. :-)