Add llms.txt?

The [llms.txt](https://llmstxt.org/) is a recently proposed standard for websites to provide structured information specifically for Large Language Models (LLMs) and other AI systems.

I noticed from Bun has one at https://bun.sh/llms.txt added in https://github.com/oven-sh/bun/issues/17017#issuecomment-2674162735
The Deno website returns 404 on visiting https://deno.com/llms.txt or https://deno.com/llms-full.txt