All the official documentation is autogenerated daily. What documentation did you find outdated?

Autogenerated documentation !== up-to-date and/or good documentation.

Autogenerated means "we take these particular strings and texts and dump them in a different format". It says nothing about whether they are even remotely up to date.

Sure, but in my experience the documentation from the source has always been correct. There is tons of stuff on other websites that is outdated, but the source documentation has not suffered the same atrophy.

More importantly, much of the documentation is auto generated not from arbitrary doc strings, but from the nix expressions themselves. IE: https://search.nixos.org/options?

So I believe there was another source of the misinformation then the official docs.

One example: nix-pills introduces nix-env -i[1] as the third "pill" -- isn't this basically deprecated and never recommended by serious uesrs?

[1]: https://nixos.org/guides/nix-pills/enter-environment.html

Most probably NixOS Wiki, it's not official but always comes up as the top result because the manual's titles are irrelevent when you're trying to solve a specific issue. The NixOS Wiki is very helpful in a lot of ways (there is more info than in the manuals and you don't have to troubleshoot for hours because you missed activating some options), butit is true that it is sometimes outdated :/