add v6.5.11 release notes

[qiancai]

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• v8.3 (TiDB 8.3 versions)
• v8.2 (TiDB 8.2 versions)
• v8.1 (TiDB 8.1 versions)
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• 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))

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: qiancai

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[qiancai]

/retest

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #18684.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #18685.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.2: #18686.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.3: #18687.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #18688.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.1: #18689.