Marking checklist

[Mic92]

We often have checklist like this: NixOS/nixpkgs#55370 (comment)

but the issue is that only nixpkgs-committers can mark them as done or relate issues to them. There could be a bot command that allows users to say something like:

@marvin-mk2 mark #55370 nixos/modules/services/network-filesystems/samba.nix

And than the bot just does simple pattern matching in the first issue post for this checkbox.