Call for maintainers

This is the followup to https://github.com/statsd/statsd/issues/649. The transfer is now done, but we still have an open call for maintainers. If you are genuinely interested in becoming a maintainer, start contributing now by e.g. commenting on issues, suggesting labels, testing PRs, writing PRs. This will help with becoming a maintainer as it

• Provides a history of contributing to the project.
• Gives you an idea of what is involved to be a maintainer, so you will know if it's something you actually are still interested in.

Then follow the steps in the maintainers doc.