Add documentation for dot product attention

[cyanguwa]

Description

Add documentation for dot product attention.

Type of change

• [x] Documentation change (change only to the documentation, either a fix or a new content)
• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

Changes

• Add documentation, example scripts, benchmarks for dot product attention. Discuss the details of supported backends, their differences, and the nuances of other features such as QKV layouts, mask types, and FP8 attention.

Checklist:

• [x ] I have read and followed the contributing guidelines
• [x ] The functionality is complete
• [x ] I have commented my code, particularly in hard-to-understand areas
• [x ] I have made corresponding changes to the documentation
• [x ] My changes generate no new warnings
• [x ] I have added tests that prove my fix is effective or that my feature works
• [x ] New and existing unit tests pass locally with my changes

[cyanguwa]

/te-ci pytorch

[cyanguwa]

/te-ci pytorch

[cyanguwa]

/te-ci pytorch

[cyanguwa]

/te-ci pytorch

[cyanguwa]

/te-ci pytorch

[cyanguwa]

/te-ci pytorch

[cyanguwa]

/te-ci pytorch

[cyanguwa]

/te-ci pytorch

[cyanguwa]

/te-ci pytorch