Final update to the changelog for v2.2.0

[jvegreg]

Last minute updates to the changelog

• Closes #issue_number
• Link to documentation:

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New or updated recipe/diagnostic:

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• 🧪 Figure(s)/data look as expected
• 🧪 Code is well documented and scientifically sound

New or updated data reformatting script:

• 🛠 Dataset is added to the table in the documentation
• 🛠 Documentation contains instructions to obtain the data
• 🛠 Tests for the CMORized data are available
• 🧪 Numbers/units of the data look physically meaningful
• 🛠 Data set is added to the OBS data pool

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