*: add extended statistics doc and update related pages

[lilin90]

What is changed, added or deleted? (Required)

• Adds a new doc named extended-statistics.md to align with the English version Introduction to Extended Statistics
• Updates affected pages related to statistics

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 (in Chinese).

• master (the latest development version)
• v8.1 (TiDB 8.1 versions)
• v8.0 (TiDB 8.0 versions)
• v7.6 (TiDB 7.6 versions)
• v7.5 (TiDB 7.5 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)

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

• This PR is translated from:
  • https://docs.pingcap.com/tidb/dev/extended-statistics
  • statistics: add some doc for the exp feature docs#9891
• Other reference link(s): add extended statistics doc #11384

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]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[lilin90]

@qiancai Thanks for your comments! All comments have been addressed via 8616084. PTAL again~

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-05-29 01:54:27.772164226 +0000 UTC m=+2827821.529299800: ☑️ agreed by qiancai.

[ti-chi-bot]

@winoros: adding LGTM is restricted to approvers and reviewers in OWNERS files.

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[lilin90]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lilin90

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• OWNERS [lilin90]

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[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #17486.