Docs: Make change-log visible in mypy documentation

[quinn-sasha]

Resolves #17717

Why

• Problem: a change log cannot be found in official mypy documentation.
• Enabling change log will improve the guidance of the official documentation.

Changes

(Explain how this PR changes mypy.)

This change will make change log visible in mypy documentation.

1. Adding MyST-Parser into requirements.txt.
2. Created changelog.md int mypy/docs/source/ to include mypy/CHANGELOG.md into mypy documentation.
3. Added change log entry into table of contents.

Checklist:

• Read the Contributing Guidelines

---

• make linkcheck
  The test had some warnings, but they were not caused from this pull request change.
• runtests.py:
  Got error FileNotFoundError: [Errno 2] No such file or directory: 'pre-commit', but I guess it has nothing to do with documentation changes
• tox run -e py

---

• Make sure CI passes.
• Do not force push to PR once reviewed

[quinn-sasha]

About documentation build error

The error said ERROR: No matching distribution found for myst-parser>=4.0.0.
Maybe, it needs lower version of myst-parser.

[hauntsaninja]

Thanks, let's see if #17747 fixes the build

[quinn-sasha]

Next warning was caused by Non-consecutive header level increase; H2 to H4 in mypy/CHANGELOG.md.

However, it is not strange that there is a increasing header level in change log.
So I added suppress_warnings = ["myst.header"] line into conf.py to suppress the warning.
reference

[webknjaz]

Don't do this. Instead, decrease the indentation in CHANGELOG.md. Look at https://github.com/python/mypy/blob/72c413d/CHANGELOG.md?plain=1#L14 — it uses #### (H4) right after ## (H2). So MyST-Parser is correct to flag this. It's a real problem that needs to be fixed rather than ignored.

[webknjaz]

Looks like it should be auto-replaced across that entire file. Running sed -i 's/^####/###/g' CHANGELOG.md should do what's needed to correct the mistake.

[quinn-sasha]

Thank you very much for your guide!

[webknjaz]

Relevant issue: #17717

@quinn-sasha

Tip

Pro tip: replace this with Resolves #17717 and GitHub will link it properly, and auto-close on merge.

[hauntsaninja]

Thank you!