Diagram demonstrating a routing scenario.
Some prose documentation.
Address review comments: Additional benefits, better transition to no-change configuration.
Merge remote-tracking branch 'refs/remotes/origin/master' into document-routing-130
Merge remote-tracking branch 'refs/remotes/origin/master' into document-routing-130
Merge pull request #170 from ClusterHQ/document-routing-130

Document routing.

Fixes #130.