Add MAINTAINERS.md

[resker]

Summary

Adds the standard NVIDIA OSS governance artifact that names the project's maintainers, and requests a decision on whether to expand the current CODEOWNERS file beyond its single default owner.

Proposed changes

1. MAINTAINERS.md (new file)

Follows the pattern used by comparable NVIDIA OSS projects where the canonical source of truth for the maintainer list is a GitHub team, not an inline markdown table — easier to keep current, no PR needed to add or remove members.

Proposed structure:

1. Current Maintainers — link to https://github.com/orgs/NVIDIA/teams/topograph-maintainers
2. Maintainer Responsibilities — review/merge PRs, triage issues, uphold the Code of Conduct, make release decisions
3. Becoming a Maintainer — selection criteria and nomination process
4. Emeritus Maintainers — _None yet_

2. .github/CODEOWNERS — expansion is optional; flagging as a decision

I'd recommend option 3 below.

Option	Shape	Tradeoff
Leave minimal / drop	* @dmitsh or no file	Matches several comparable NVIDIA OSS projects. Simplest.
Two-handle default	* @dmitsh @ravisoundar	Immediate fix for single-reviewer bottleneck. No team dependency.
Two-tier teams	* @nvidia/topograph-write default + @nvidia/topograph-maintainers on critical paths (pkg/topology/, protos/, /charts/, /.github/, governance files)	Structurally enforces the "do not change without discussion" guidance in AGENTS.md. Requires both GitHub teams to exist first.

Seeking maintainer input on which direction fits current review capacity.

Dependencies

• The team-delegation pattern (option 3 for CODEOWNERS, and the MAINTAINERS.md link target) requires two GitHub teams at the org level:
  • @nvidia/topograph-maintainers
  • @nvidia/topograph-write
• @dmitsh is coordinating team creation. MAINTAINERS.md and any team-referencing CODEOWNERS can land once the teams exist.
• The simpler CODEOWNERS options (leave as-is, or two-handle default) have no dependency and can land immediately if preferred.

Non-goals

• Not changing who the maintainers are
• Not proposing a maintainer-promotion process change
• Not altering the DCO policy or review requirements