docs: Refine OpenClaw reference and feature descriptions

[Koimiao-zz]

Updated the README to simplify the OpenClaw reference and improve clarity.

📝 Pull Request Summary

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✅ What does this PR do?

• Clearly describe the change introduced.
• Mention the motivation or problem it solves.

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🤔 Why is this change needed?

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🔍 Type of Change

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• Bug fix
• New feature
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✅ PR Quality Checklist

• PR title follows the conventional format (feat:, fix:, docs:)
• Changes are limited in scope and easy to review
• Documentation updated where applicable
• No breaking changes (or clearly documented)
• Related issues or discussions linked

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📌 Optional

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