llms.txt

### Is there an existing issue for this?

- [x] I have searched the existing issues

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

Thank you for creating and maintaining this fantastic repo!
With the rise of LLM-powered tools, it would be super helpful to provide an llms.txt file so models like ChatGPT can better understand and use the project.

### Describe the solution you'd like.

prepare a file with links of markdown that contains api description and case examples
```bash
pip install llms-txt
llms_txt2ctx llms.txt > llms-ctx.txt
```