the simplest for that is: in each directory you add a OWNERS (or CODEOWNERS) file, eg:
[https://github.com/dlang/dmd/blob/master/CODEOWNERS](https://github.com/dlang/dmd/blob/master/CODEOWNERS) (easily machine-parseable in case we need tooling) that way it's version controlled and ppl can put themselves out when they no longer want to be involved in some part of the code
