update MariaDB documentation links from kb/ to docs/

[Oreoxmt]

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What is changed, added or deleted? (Required)

close #20964

The MariaDB Knowledge Base has been migrated to a new documentation platform (mariadb.com/docs/). Many links using the old kb/ path structure are now broken (returning 404 errors) or being redirected, which impacts user experience and documentation reliability.

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For details, see tips for choosing the affected versions.

• master (the latest development version)
• v9.0 (TiDB 9.0 versions)
• v8.5 (TiDB 8.5 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)
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[qiancai]

Rest LGTM

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-09-30 02:40:07.473780249 +0000 UTC m=+138787.730511649: ☑️ agreed by qiancai.

[Oreoxmt]

/approve

[ti-chi-bot]

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[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #20969.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.5: #20970.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.1: #20971.
But this PR has conflicts, please resolve them!

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #20972.