Org owner rotation and member updates

[infinisil]

As decided by the SC (with approvals from at least @K900, @cafkafk, @JulienMalka and @philiptaron):

Proposal: Shared Team Membership Rotation policy for GitHub Org Owner and Enterprise Admin access.

1. The represented teams are the Steering Committee, the Foundation board, the Security team, and the Nixpkgs core team.
2. For the initial bootstrap, each team nominates a representative per its own decision procedures, and the Steering Committee then votes on approving the new set of org owners as a whole.
3. At any time, a team can withdraw its representative per its own decision procedures. The Steering Committee can also vote to remove a representative.
4. If a represented team's seat is vacant or expected to become vacant, it can nominate a replacement per its own decision procedures. The Steering Committee then votes on approving the replacement representative.
5. The responsibilities and procedures at https://github.com/NixOS/org/blob/main/doc/github-org-owners.md remain in place as-is for day to day work.
6. The Steering Committee remains the final authority and can vote to amend org owner procedures at any time. Concerns about trustworthiness, activity, or procedures can be raised through the usual channels.

This proposal keeps the representation of the board for legal/financial matters, the SC as a representative for elected governance, and improves our security posture by reducing the total number of org owners and bringing in relevant expertise. It also improves the health of org owner decision-making by naturally ensuring the "two-person decisions require sign-off from multiple teams" property.

This PR implements it by updating the org owners documentation according to the proposal and the team-chosen representatives.

The SC already approved the final team composition with yays from everybody present in the meeting (@K900, @JulienMalka, @roberth, @philiptaron, @tomberek and @Ericson2314) and only @cafkafk absent.

Ping @NixOS/org @NixOS/security @NixOS/nixpkgs-core @NixOS/foundation @NixOS/steering

[winterqt]

Thanks to all who made this happen :)

[winterqt]

I’m free from my shackles!

[JulienMalka]

Thanks to the outgoing team! @winterqt @tomberek @Lassulus

[Lassulus]

One less hat!!

[infinisil]

Since I don't think there's a hurry, I'd say let's allow a day for feedback to the specific wording. If all looks good I'll merge and implement this on Friday.