v0.1.1

The worker, the public API and the database schema are unchanged. This
release updates the packaging metadata and the project description that
appears on the package page.

Changed

• Packaging metadata now carries a Documentation URL, so the
  documentation site is linked directly from the package page.
• README now carries release and CI status badges, a link to the
  documentation site, and a scope statement: what the core covers, what is
  deliberately outside it, and which features belong to the commercial
  tier.