Merge release/v2.33.1 release notes into develop

[serban-nicusor-toptal]

Submisison Checklist

• [ ] Run tests: ./runCmdStanTests.py src/test
• [ ] Declare copyright holder and open-source license: see below

Summary:

Merge release/v2.33.1 release notes into develop

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Copyright and Licensing

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• Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
• Documentation: CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)