Add CODEOWNERS for GAP-13

[magicmark]

Add a CODEOWNERS file granting @benjie ownership of the GAP-13 directory.

questions/confirmations for @benjie:

1. adding even though the directory doesn't exist yet (b/c the PR hasn't been merged; this step is (currently) first
2. do we want to namespace GAP-N directories in a top level gaps folder? I would think yes actually, but CONTRIBUTING doesn't clarify and package.json encodes that they'd all top level. I think we should change this?
3. would editors require another person to give approval on this type of PR? (General etiquette in the absence of explicit rules is to not self-merge)

[benjie]

Hmmm…

Should GAPS be root level?

Good question.

Pro: simplicity, instant visibility.
Con: messy root.

Gut says you’re right and we should move it to gaps/N/ or gaps/GAP-N/

When to add?

Adding it via GitHub action after merge makes most sense to me. We don’t care that pushed commit won’t have secondary actions fired, it’s admin only.

However it does reveal that the author’s github handle should be in the authors entry - authors should be list of objects maybe?

If done in the current order it should be added to the user’s PR by an editor, if permissions allow. If not, it should be an editor that follows the merge.

Requires approval?

Editors can follow the procedures for admining the repo without needing approval. For merging a gap it might make sense to require “All editor/TSC feedback addressed, plus either two editor/TSC approvals from different organisations, or one approval and a 7-day wait for feedback” but I’m not really sure we need the delay. Probably we should block merging of your own GAP.

[magicmark]

Editors can follow the procedures for admining the repo without needing approval.

ack, merging this PR.

Gut says you’re right and we should move it to gaps/N/ or gaps/GAP-N/

++, let's go with gaps/GAP-123 (https://github.com/python/peps/tree/main/peps)

[magicmark]

authors should be list of objects maybe?

makes sense, I like that this implies that CODEOWNERS can always be reproduced by reading all gap metadata.yml files, and any transfer in authorship will be kept up to date in CODEOWNERS too.

and then yeah we can entirely forget about manually maintaining this file and document who adds it and when etc.