Manual entry on IFD does not consider store paths not produced by derivations

Problem

The manual entry states:
https://github.com/NixOS/nix/blob/4e8a9e0ed4ce9edcaec4e7939e3bfff2f060edb8/doc/manual/src/language/import-from-derivation.md?plain=1#L7

However, "an expression expr that evaluates to a store path" does not necessarily involve a derivation. It may also be produced by a built-in fetcher.

Nix also agrees that builtins.fetchurl is not IFD:

let
  pkgs = import <nixpkgs> {};

  name = "funny.txt";
  url = "https://example.com";
  sha256 = "sha256-6o+sfGX7WJsNU1YPUlH3T56bJDR43Laz6nm142RJyNk=";
in
{
  viaBuiltins = builtins.readFile (builtins.fetchurl {
    inherit name url sha256;
  });
  viaPkgs = builtins.readFile (pkgs.fetchurl {
    inherit name url sha256;
  });
}

$ nix eval -f example.nix --no-allow-import-from-derivation viaPkgs
error:
       … while calling the 'readFile' builtin
         at /tmp/tmp.sjf6pjcR2J/example.nix:12:13:
           11|   });
           12|   viaPkgs = builtins.readFile (pkgs.fetchurl {
             |             ^
           13|     inherit name url sha256;

       … while realising the context of path '/nix/store/ppsywqzjm5v8nvki3swzx4zrri55ppcp-funny.txt'

       error: cannot build '/nix/store/5x8v83jldidwrn9vg8w9wr9y2r3x04p4-funny.txt.drv^out' during evaluation because the option 'allow-import-from-derivation' is disabled

$ nix eval -f example.nix --no-allow-import-from-derivation viaBuiltins
"[html content of example.com]"

Proposal

The paragraph should somehow mention that it's only IFD when the store path is produced by a derivation. The existing sentence is already pretty long and complex, so maybe using a list would make it easier to understand:

Import From Derivation (IFD) occurs when:

• an expression expr, which evaluates to a store path
• is passed to any built-in function which reads from the filesystem
• and the store path in question is an output path of a derivation

The following are built-in functions reading from the filesystem:

(the existing list of functions)

Checklist

• checked latest Nix manual (source)
• checked open documentation issues and pull requests for possible duplicates

Priorities

Add 👍 to issues you find important.

Open doc/manual/src/language/import-from-derivation.md and read the linked paragraph describing when IFD occurs. Revise the wording to distinguish derivation output paths from other store paths, then check the rendered manual to confirm the explanation and existing function list remain clear.