Add llms.txt support to improve AI/LLM visibility

[zeljkoX]

Large language models like ChatGPT, Claude, and Perplexity are becoming a primary way users discover our docs. They don’t crawl sites like Google — they grab content on the fly and skip noisy HTML.

llms.txt is an emerging convention that acts as a lightweight, Markdown guide for AI crawlers. It points models to our canonical docs, structured exports, and most important pages so we get accurate, up-to-date citations instead of stale or duplicate content.

Examples:

• https://docs.stripe.com/llms.txt
• https://docs.midnight.network/llms.txt