Google and duckduckgo link to docs for very old versions of pyo3

[hoodmane]

If I google for pyo3, I find:
https://pyo3.rs/v0.10.1/
DuckDuckGo gives me:
https://pyo3.rs/v0.15.1/

Both for quite old versions. Not sure whether there is anything that you all can fix here, but thought you might like a heads up.

[davidhewitt]

I think we should be able to set headers on the netlify pages to force search engines to index only the latest docs. I last attempted this in #3264 but likely missed something.