information-schema: add the description about hot region statistical cycle

[Oreoxmt]

What is changed, added or deleted? (Required)

Add the description about hot region statistical cycle.

Which TiDB version(s) do your changes apply to? (Required)

Tips for choosing the affected version(s):

By default, CHOOSE MASTER ONLY so your changes will be applied to the next TiDB major or minor releases. If your PR involves a product feature behavior change or a compatibility change, CHOOSE THE AFFECTED RELEASE BRANCH(ES) AND MASTER.

For details, see tips for choosing the affected versions.

• master (the latest development version)
• v7.6 (TiDB 7.6 versions)
• v7.5 (TiDB 7.5 versions)
• v7.4 (TiDB 7.4 versions)
• v7.3 (TiDB 7.3 versions)
• v7.1 (TiDB 7.1 versions)
• v6.5 (TiDB 6.5 versions)
• v6.1 (TiDB 6.1 versions)
• v5.4 (TiDB 5.4 versions)
• v5.3 (TiDB 5.3 versions)
• v5.2 (TiDB 5.2 versions)
• v5.1 (TiDB 5.1 versions)
• v5.0 (TiDB 5.0 versions)

What is the related PR or file link(s)?

• This PR is translated from: information-schema: add the description about hot region statistical cycle docs-cn#16395
• Other reference link(s):

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-chi-bot]

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[qiancai]

Removed the needs-cherry-pick-release-7.3 label because the v7.3 docs have been archived at https://docs-archive.pingcap.com/tidb/v7.3 and will no longer receive new updates.

[qiancai]

Removed the needs-cherry-pick-release-7.4 label because the v7.4 docs have been archived at https://docs-archive.pingcap.com/tidb/v7.4 and will no longer receive new updates.

[ti-chi-bot]

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[qiancai]

Removed the needs-cherry-pick-release-7.6 label because the v7.6 docs have been archived at https://docs-archive.pingcap.com/tidb/v7.6 and will no longer receive new updates.

[qiancai]

Removed the needs-cherry-pick-release-8.0 label because the v8.0 docs have been archived at https://docs-archive.pingcap.com/tidb/v8.0 and will no longer receive new updates.