doc: Use hierarchical readme for publishing

[jokemanfire]

1.Added readme for each crate package
2.The introduction of the document has been reorganized to make the top-level document clearer

Motivation and Context

The document is not clear enough

How Has This Been Tested?

Breaking Changes

No

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 change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context