Fix typos in tiup-cluster.md (#5202)

[ti-srebot]

cherry-pick #5202 to master
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# In docs repo:
git pr https://github.com/pingcap/docs/pull/5418

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git push git@github.com:ti-srebot/docs.git pr/5418:master-c391b7cc269f

---

minor typo -

First-time contributors' checklist

• I've signed Contributor License Agreement that's required for repo owners to accept my contribution.

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• master (the latest development version)
• v5.0 (TiDB 5.0 versions)
• v4.0 (TiDB 4.0 versions)
• v3.1 (TiDB 3.1 versions)
• v3.0 (TiDB 3.0 versions)
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Do your changes match any of the following descriptions?

• Delete files
• Change aliases
• Need modification after applied to another branch
• Might cause conflicts after applied to another branch

[ti-srebot]

@rkazak please accept the invitation then you can push to the cherry-pick pull requests.
https://github.com/ti-srebot/docs/invitations

[TomShawn]

/label require-LGT1
/lgtm

[ti-chi-bot]

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• TomShawn

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[TomShawn]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 11a6598