release: v0.20.0 - #458

release-please builds its sections from commit type, so test: and docs: commits
never reach them. In this cut that is nine of fourteen commits and most of the
work: the run counting itself, the last hand-written figure leaving the summary,
the object and scene doctrine, the roadmap, and two toolchain silences.

The generated sections are accurate and they are the smaller half. The narrative
above them says so first, so a reader does not take the four lines for the cut.