improve guidance for how to include VRRM in a larger application

[evanmcc]

If anyone else is ever to use this, I need to provide some decent documentation, which should center on usage examples and accrued experience with operating VRRM-including clusters.

Also helpful would be a rich group of basic replicated state machines for people to use.

• replicated map
• replicated multi-counter
• replicated sets
• replicated flags

At least one more advanced example would be good, but I can't think of one right off hand. Perhaps a replicated (i.e. HA) uptime checker (this might also exercise transitions originating from within the statem)?

Ideally there would be one decent example application, like a HA SC configuration store a la Chubby/etcd.

I'd also like to either include or write separately a SC erlang registry/pg server.