docs(schedule/timezone): rewrite

[HonkingGoose]

Changes

• Use one sentence per line pattern.
• Split a long block of text into two parts, with a paragraph.
• Replace emoji ✅ with plain text Yes.
• In the timezone docs, use a list instead of a long sentence, and rewrite the section.

Context

Follow up PR after:

• docs(schedule): improve description, deprecate Later syntax #31958

I'm not closing any issue with this PR.

Documentation (please check one with an [x])

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• No documentation update is required

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I have verified these changes via:

• Code inspection only, or
• Newly added/modified unit tests, or
• No unit tests but ran on a real repository, or
• Both unit tests + ran on a real repository

[renovate-release]

🎉 This PR is included in version 38.126.2 🎉

The release is available on:

• GitHub release
• npm package (@latest dist-tag)
• 38.126.2

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