Release of v15.0.1

[rsajwani]

Includes the release notes and tag commit for the v15.0.1 release.

[vitess-bot]

Review Checklist

Hello reviewers! 👋 Please follow this checklist when reviewing this Pull Request.

General

• Ensure that the Pull Request has a descriptive title.
• If this is a change that users need to know about, please apply the release notes (needs details) label so that merging is blocked unless the summary release notes document is included.

If a new flag is being introduced:

• Is it really necessary to add this flag?
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• Flag names should use dashes (-) as word separators rather than underscores (_).

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Bug fixes

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• The Pull Request description should include a link to an issue that describes the bug.

Non-trivial changes

• There should be some code comments as to why things are implemented the way they are.

New/Existing features

• Should be documented, either by modifying the existing documentation or creating new documentation.
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Backward compatibility

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