fix the recommended range for region-split-size

[qiancai]

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• This PR is translated from: fix the recommended range for region-split-size docs-cn#18187
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[lilin90]

/lgtm

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[LGTM Timeline notifier]

Timeline:

• 2024-07-29 08:12:15.76700659 +0000 UTC m=+170652.047054652: ☑️ agreed by lilin90.

[qiancai]

/approve

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[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.1: #18405.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #18406.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.1: #18408.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #18409.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.0: #18410.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #18411.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.2: #18412.