Polish the Catalyst 0.9.0 Changelog and Documentation

[joeycarter]

Applies a number of minor editorial changes and polishing to the Catalyst v0.9.0 changelog and related documentation, including

• Spelling and grammar corrections, improved readability
• Consistent Python code-snippet formatting
• Use the present tense, where applicable, e.g. "Resolves a bug where..."
• Wrap lines at 100 characters
• Sort the "Contributors" alphabetically by last name

[github-actions[bot]]

Hello. You may have forgotten to update the changelog! Please edit doc/releases/changelog-dev.md on your branch with:

• A one-to-two sentence description of the change. You may include a small working example for new features.
• A link back to this PR.
• Your name (or GitHub username) in the contributors section.

[joeycarter]

Hello. You may have forgotten to update the changelog! Please edit doc/releases/changelog-dev.md on your branch with:

* A one-to-two sentence description of the change. You may include a small working example for new features.

* A link back to this PR.

* Your name (or GitHub username) in the contributors section.

No need to update the dev changelog to record that I've updated the release changelog :slightly_smiling_face:.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Please upload report for BASE (v0.9.0-rc@3fd7b6d). Learn more about missing BASE report.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## v0.9.0-rc #1238 +/- ## ============================================ Coverage ? 97.95% ============================================ Files ? 77 Lines ? 11319 Branches ? 981 ============================================ Hits ? 11088 Misses ? 181 Partials ? 50 ```

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