### Motivation and Context
Publish an [`llms.txt`](https://llmstxt.org/) at the ONNX docs site root
— the
convention OpenAI, Anthropic, and Google already use for their own docs
— so
AI agents and other automated tooling can navigate the ONNX
documentation
(operator reference, IR spec, versioning, shape inference, etc.) without
having to crawl the whole site.
### What changed
- `docs/docsgen/source/extra/llms.txt`: a curated index page — project
summary plus links to the operator reference, IR specification, textual
syntax, Python API, and contributing docs.
- `docs/docsgen/source/conf.py`: added `html_extra_path = ["extra"]` so
Sphinx copies the file verbatim to the build root (`llms.txt` next to
`index.html`) instead of nesting it under `_static/`.
This is purely additive: one new file plus one config line. No existing
page's content, URL, or build behavior changes, and no new dependency is
introduced.
### Testing
Ran `pixi run -e docs docs-build` locally and confirmed the build
succeeds
and `docs/docsgen/build/html/llms.txt` is produced with the expected
content. The `pages.yml` workflow will build this PR's docs for further
verification.
Signed-off-by: Andreas Fehlner <fehlner@arcor.de>
Andreas Fehlner
b9c537e753
