[Feat]: Please provide documentation for TCK and ITK

### Is your feature request related to a problem? Please describe.

A2A provides TCK and ITK but as a user there is a confusion of what they are & how to use.

### Describe the solution you'd like

A page describing what they are, how are they are useful, when to use, how to use(a mock example)

### Describe alternatives you've considered

Provide information for Agents.md

### Additional context

_No response_

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct