docs: add no-data slot documentation

[gweesin]

Add documentation for no-data slot of data table.

Closed #4494

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [x] Improvement/refactoring (non-breaking change that doesn't add any feature but make things better)

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