en,zh: add v1.5.2 release notes

[csuzhangxc]

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• v1.5 (TiDB Operator 1.5 versions)
• v1.4 (TiDB Operator 1.4 versions)
• v1.3 (TiDB Operator 1.3 versions)
• v1.2 (TiDB Operator 1.2 versions)

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[ran-huang]

/approve

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[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-1.5: #2495.