Enforces who can approve changes

[benoit-cty]

Description

The CODEOWNERS file actually serves both purposes - it automatically requests reviews AND enforces who can approve changes when combined with GitHub's branch protection rules.

To achieve what you want (only @mlco2/core-maintainers can merge), you need to:

Keep the CODEOWNERS file as is - it's already correct
Configure branch protection rules in GitHub repository settings:
Go to: Settings → Branches → Branch protection rules
Add/edit rule for master (or your main branch)
Enable: "Require review from Code Owners"
Enable: "Require approvals" (set to at least 1)
Optionally enable: "Dismiss stale pull request approvals when new commits are pushed"
With these settings:

✅ Only members of @mlco2/core-maintainers can approve PRs
✅ PRs cannot be merged without approval from code owners
✅ Other contributors can review/comment but cannot approve/merge
The CODEOWNERS file you have is already set up correctly for this purpose. The enforcement happens through GitHub's branch protection settings, not the CODEOWNERS file itself.

Related Issue

Will close #865

Motivation and Context

Limit who could merge to master, so we could add more people as contributors.

How Has This Been Tested?

Types of changes

What types of changes does your code introduce? Put an x in all the boxes that apply:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

Go over all the following points, and put an x in all the boxes that apply.

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING.md document.
• I have added tests to cover my changes.
• All new and existing tests passed.