fix: point _index.md TiDB Self-Managed links to stable instead of unpublished v8.5

[yahonda]

What is changed, added or deleted? (Required)

_index.md's "TiDB Self-Managed" page had 38 reference links pointing to
https://docs.pingcap.com/ja/tidb/v8.5/..., but the Japanese v8.5 docs are
not published yet, so every one of these links 404s. This PR points all
38 links at stable instead, which resolves correctly for every path.

Verified before/after for all 36 unique paths used in this file:

• Before: https://docs.pingcap.com/ja/tidb/v8.5/<path> -> 404 (all 36)
• After: https://docs.pingcap.com/ja/tidb/stable/<path> -> 200 (all 36)

Originally flagged by CodeRabbit on PR #23832 (a separate configuration-terminology PR) for just one of these 38 links (tidb-configuration-file); a repo-wide check found only 2 other files reference /ja/tidb/v8.5/ at all, and both are aliases: front-matter entries (a page's own future-alias declaration, not a clickable link), so out of scope here.

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

• i18n-ja-release-8.5 (TiDB Japanese documentation for TiDB 8.5 versions)

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

• This PR is translated from:
• Other reference link(s): flagged by CodeRabbit on i18n(ja): unify configuration file/parameter terminology (part 1/2) #23832 (comment)

AI agent involvement

• The changes in this PR were primarily made by an AI agent on behalf of the PR author.

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

🤖 Generated with Claude Code

Summary by CodeRabbit

• Documentation
  • Updated Japanese TiDB Self-Managed navigation links to use stable documentation paths across the Learn, Try, Deploy, Migrate, Maintain, Monitor, Tune, Tools, and Reference sections.
  • Updated the Kubernetes deployment link to the stable TiDB in Kubernetes documentation path.
  • Kept the release-notes link unchanged.

[coderabbitai]

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• _index.md

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📝 Walkthrough

Walkthrough

Japanese TiDB Self-Managed navigation links now use stable documentation paths. The Kubernetes deployment link uses the tidb/stable/tidb-in-kubernetes/ path. The release-notes link remains unchanged.

Changes

Japanese navigation links

Layer / File(s)	Summary
Update navigation documentation paths _index.md	Learn, Try, deployment, migration, maintenance, monitoring, tuning, tools, and reference links use stable instead of v8.5. The Kubernetes link uses the new stable path. The release-notes link is unchanged.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~5 minutes

Change: Bug fix

Merge Risk: ⚪ Minimal · up to 87469

The navigation links are updated to stable documentation paths, with no remaining merge-blocking issue identified.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: updating TiDB Self-Managed links from the unpublished v8.5 path to the stable path.
Description check	✅ Passed	The description explains the reason for the change, the affected file and links, verification results, applicable version, reference link, AI involvement, and change-category checkboxes. The first-tim…
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[yahonda]

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• _index.md

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[LGTM Timeline notifier]

Timeline:

• 2026-09-15 13:32:43.706753393 +0000 UTC m=+125609.644410977: ☑️ agreed by qiancai.