Governance improvement checklist

This issue provides a checklist for enhancing governance in the Peerd project:

## Repository Settings

- [x] Add a `CODEOWNERS` file in the root of the repository. See [the guideline](https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/about-code-owners) and [an example](https://github.com/notaryproject/notation/blob/main/CODEOWNERS).
- [x] Add a `MAINTAINERS` file in the root of the repository to list organization maintainers and repository maintainers. See [an example](https://github.com/notaryproject/notation/blob/main/MAINTAINERS).
- [x] Set up branch protection rules, such as the number of reviewers required. See [the guide](https://docs.github.com/en/repositories/configuring-branches-and-merges-in-your-repository/managing-protected-branches/about-protected-branches).

## Contributing Guide

- [ ] Update the existing [contributing guide](https://github.com/Azure/peerd/blob/main/CONTRIBUTING), see [the guide and examples](https://contribute.cncf.io/maintainers/templates/contributing/).

## Governance related documents:

Refer to the [CNCF governance model](https://contribute.cncf.io/maintainers/governance/) for a good reference.

- [ ] Add `GOVERNANCE.md`, including oles, responsibilities, decision-making, and leadership election. See [the guide and examples](https://contribute.cncf.io/maintainers/governance/leadership-selection/).
- [ ] Add governance on contributor promotion, see [the template](https://github.com/cncf/project-template/blob/main/CONTRIBUTOR_LADDER.md), and [example](https://github.com/notaryproject/.github/blob/main/CONTRIBUTOR_LADDER.md).
- [ ] Add the charter document, see [the guide and examples](https://contribute.cncf.io/maintainers/governance/charter/).
- [ ] Add the roadmap doc, see [the guideline](https://contribute.cncf.io/maintainers/community/contributor-growth-framework/open-source-roadmaps/) and an [example](https://fluxcd.io/roadmap/).

## Issue management
- [ ] Add [issue templates](https://docs.github.com/en/communities/using-templates-to-encourage-useful-issues-and-pull-requests/about-issue-and-pull-request-templates), see [an example](https://github.com/notaryproject/notation/tree/main/.github/ISSUE_TEMPLATE).
- [ ] Document how issue labels are managed. Github provides [default labels](https://docs.github.com/en/issues/using-labels-and-milestones-to-track-work/managing-labels#about-default-labels), see [an example](https://github.com/notaryproject/.github/blob/main/CONTRIBUTING.md#labels).

## Other documents
- [ ] Add a release management document, see [an example](https://argo-cd.readthedocs.io/en/latest/developer-guide/release-process-and-cadence/).
- [ ] Add a communication document, see [an example](https://github.com/helm/community/blob/main/communication.md).