Coredns: Use bot for coredns

[miekg]

I forked Derek and wrote Dreck: https://github.com/miekg/dreck that can help with PRs and issues. It's a bit underdocumented, but it can run as a caddy plugin and I'll set up dreck.miek.nl for it to serve off.

allows you to do things (if you're in the top-level OWNERS) file:

~
/assign: user
~
to assign to a user and multiple other things - this stuff also works from email.

I'm pondering to add auto-assign to assign reviewers on PRs based on the OWNERS file, but that isn't implemented yet.

[stp-ip]

For ideas: https://github.com/kubernetes/test-infra/tree/master/prow

[miekg]

I've reworked Dreck a bit and installed it as CorBot on the CoreDNS organisation.

I'll enable it, but updating the top-level OWNERS file

[miekg]

This is live now.