docs: recommend setting moduleLocation by default

[Atry]

As moduleLocation can be used to avoid portential infinite loops issue, it would be nice to mention it from README.

[roberth]

Is that still needed? Did you run into this again?
If users set inputs (which almost certainly they do), Nix will use the attribute position to determine the file.
That's since #192; half a year ago.

[Atry]

moduleLocation can be used to locate ./. to avoid stack overflow. See https://github.com/Atry/nix-ml-ops/blob/f37e70da4b6a26dbf8ca06741b87b2676f6996d5/flake-modules/poetry2nix.nix#L55-L59

[Atry]

Currently flake modules are not able to visit ./.. self.outPath is similar but it can result in infinite loops and stack overflow.

[roberth]

Currently flake modules are not able to visit ./.. self.outPath is similar but it can result in infinite loops and stack overflow.

It seems to work fine nowadays. Example: https://github.com/srid/haskell-flake/blob/e47512f9a1eda70c762a0265cf029ecdaa9ffdf3/nix/modules/project/default.nix#L19-L29

Do you have an example where moduleLocation must be set?

I'd like to avoid a situation where we make unnecessary recommendations, and I'm making an effort to make Nix provide the info robustly without unsafeGetAttrPos or self. (NixOS/nix#8908, currently blocked on a decision for NixOS/nix#10350)