We should have a Readme section, or a sample, or maybe both, to describe what we do with distributed tracing.

This should include a lien to https://github.com/cloudevents/spec/blob/master/extensions/distributed-tracing.md
This should explain our auto-magic behavior to populate the extension if we detect the HTTP headers.