two-data-centers-in-one-city-deployment.md: fix some typos

[Liuxiaozhen12]

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[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• TomShawn

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[TomShawn]

LGTM

[TomShawn]

/merge

[ti-chi-bot]

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

Commit hash: b1dc5d4