Add llms.txt to support modern AI-assisted coding workflows

[yigitkonur]

Many developers are transitioning to AI-assisted coding tools like Cursor and Windsurf. To better support these workflows, I've created llms.txt - a comprehensive context file that combines our Python cookbook examples and REST API reference documentation into a single, AI-friendly format.

This addition will help developers who use AI coding assistants to:

• Better understand R2R's capabilities and patterns
• Get more accurate code completions and suggestions
• Have proper context when generating code through LLM tools

I've tested this consolidated format with tools like o1 mini across multiple documentation sources, and it significantly improves the AI's understanding of our codebase and APIs.

The file format follows the emerging llms.txt standard (https://llmstxt.org/), making it compatible with various AI coding assistants.

Note: This will require maintenance as docs are updated, but the benefits to developer experience should outweigh the overhead.

Let me know if you'd like to see any changes to the format or content organization.

[ellipsis-dev]

Skipped PR review on 5b553f7 because no changed files had a supported extension. If you think this was in error, please contact us and we'll fix it right away.

[NolanTrem]

Thanks for making this PR, it's a great addition. I'm curious how you generated it—especially since we are still actively developing and would likely need to regenerate often.

[yigitkonur]

Hey Nolan,

Collecting and reorganizing all your docs and cookbooks with o1-pro is currently quite manual. You could automate this process using scripts, similar to how unstructured.io handles their meta prompts (see: https://docs.unstructured.io/llms-full.txt).