Writing docs for Github-related things

> **Documenting more details of the GitHub workflow.**
>
> “CONTRIBUTING.md” already has information on this, but I think it would be good to explicitly document how, when, and by whom some of the special tags like “merge me”, “backport”, or milestones should be used.
>
> —— https://discourse.julialang.org/t/about-julias-development-policy-regarding-windows/128011/55

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See also:

> ### [Issues and triaging](https://devguide.python.org/triage/)
>
> * [Issue tracker](https://devguide.python.org/triage/issue-tracker/)
>
> * [Using the issue tracker](https://devguide.python.org/triage/issue-tracker/#using-the-issue-tracker)
> * [Disagreement with a resolution on the issue tracker](https://devguide.python.org/triage/issue-tracker/#disagreement-with-a-resolution-on-the-issue-tracker)
> * [Triaging an issue](https://devguide.python.org/triage/triaging/)
>
> * [Checklist for triaging](https://devguide.python.org/triage/triaging/#checklist-for-triaging)
> * [Helping triage issues](https://devguide.python.org/triage/triaging/#helping-triage-issues)
> * [GitHub labels](https://devguide.python.org/triage/labels/)
> * [GitHub issues for BPO users](https://devguide.python.org/triage/github-bpo-faq/)
> * [Triage Team](https://devguide.python.org/triage/triage-team/)
>
> * [Becoming a member of the Python triage team](https://devguide.python.org/triage/triage-team/#becoming-a-member-of-the-python-triage-team)