Codebase Stewardship lifecycle diagram is wrong: lacks exit points

[ericherman]

In https://about.publiccode.net/activities/codebase-stewardship/lifecycle-diagram.html there is no exit from incubation except to full stewardship, whereas in practice we see that codebase communities can run out of ambition during the incubation.

A close look should be taken at each stage to see how to phrase additional gates and exits.