Update the metadata for the Review Bot packages.

Review Request #10110 — Created July 30, 2018 and submitted — Latest diff uploaded

Information

ReviewBot
release-1.0.x
c83bbdf...

Reviewers

This adds the new READMEs to the Review Bot extension and worker
packages. It also updates the classifiers to promote the stability level
to Production/Stable, add the Quality Assurance topic, and adds the
Python versions.

Built the packages and checked the resulting metadata for the README and
the classifiers.