docs(release-8.5): add STATS_DELTA to keywords.md

[Copilot]

STATS_DELTA is a non-reserved keyword in the TiDB release-8.5 parser but was missing from keywords.md, causing the weekly keywords check to fail.

What is changed, added or deleted? (Required)

Fix Weekly keywords check: mismatches found · Issue #22954 · pingcap/docs

• Added STATS_DELTA as a non-reserved keyword in keywords.md, in alphabetical order between STATS_COL_LIST and STATS_EXTENDED.

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)
• v8.5 (TiDB 8.5 versions)
• v8.4 (TiDB 8.4 versions)
• v8.3 (TiDB 8.3 versions)
• v8.2 (TiDB 8.2 versions)
• v8.1 (TiDB 8.1 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)

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

• This PR is translated from: docs(release-8.5): add STATS_DELTA to keywords.md docs#22956

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]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[ti-chi-bot]

Hi @copilot. Thanks for your PR.

I'm waiting for a pingcap member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[lilin90]

/ok-to-test

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2026-05-27 09:42:39.259218579 +0000 UTC m=+431629.229383636: ☑️ agreed by qiancai.