Add tab sync example

[ethanpalm]

Documentation changes

This PR copy edits content about tab sync and adds an example of disabling it.

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For Reviewers

When reviewing documentation PRs, please consider:

✅ Technical accuracy

• Code examples work as written
• Commands and configurations are correct
• Links resolve to the right destinations
• Prerequisites and requirements are accurate

✅ Clarity and completeness

• Instructions are clear and easy to follow
• Steps are in logical order
• Nothing important is missing
• Examples help illustrate the concepts

✅ User experience

• A new user could follow these docs successfully
• Common gotchas or edge cases are addressed
• Error messages or troubleshooting guidance is helpful

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Note

Low Risk
Documentation-only changes (copy edits and example snippet) with no runtime code impact; risk is limited to potential confusion if the MDX example is incorrect.

Overview
Updates the Tabs documentation to better explain cross-page tab synchronization using matching titles (including syncing with code groups).

Adds a concrete MDX example showing how to disable syncing via sync={false}, and moves the sync property documentation into the main Properties section with updated wording ("titles" vs "labels").

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[dino475]

LGTM