doc: make ./doc-support/lib-function-docs.nix callPackage style

Move `libsets` over to it, since it's the only user.

Format with `nixfmt` since we're changing it so dramatically.

doc/doc-support/lib-function-docs.nix

@@ -1,23 +1,111 @@
 # Generates the documentation for library functions via nixdoc.
 
-{ pkgs, nixpkgs, libsets }:
+{
+  lib,
+  stdenvNoCC,
+  nixdoc,
+  nix,
+  nixpkgs ? { },
+  libsets ? [
+    {
+      name = "asserts";
+      description = "assertion functions";
+    }
+    {
+      name = "attrsets";
+      description = "attribute set functions";
+    }
+    {
+      name = "strings";
+      description = "string manipulation functions";
+    }
+    {
+      name = "versions";
+      description = "version string functions";
+    }
+    {
+      name = "trivial";
+      description = "miscellaneous functions";
+    }
+    {
+      name = "fixedPoints";
+      baseName = "fixed-points";
+      description = "explicit recursion functions";
+    }
+    {
+      name = "lists";
+      description = "list manipulation functions";
+    }
+    {
+      name = "debug";
+      description = "debugging functions";
+    }
+    {
+      name = "options";
+      description = "NixOS / nixpkgs option handling";
+    }
+    {
+      name = "path";
+      description = "path functions";
+    }
+    {
+      name = "filesystem";
+      description = "filesystem functions";
+    }
+    {
+      name = "fileset";
+      description = "file set functions";
+    }
+    {
+      name = "sources";
+      description = "source filtering functions";
+    }
+    {
+      name = "cli";
+      description = "command-line serialization functions";
+    }
+    {
+      name = "generators";
+      description = "functions that create file formats from nix data structures";
+    }
+    {
+      name = "gvariant";
+      description = "GVariant formatted string serialization functions";
+    }
+    {
+      name = "customisation";
+      description = "Functions to customise (derivation-related) functions, derivatons, or attribute sets";
+    }
+    {
+      name = "meta";
+      description = "functions for derivation metadata";
+    }
+    {
+      name = "derivations";
+      description = "miscellaneous derivation-specific functions";
+    }
+  ],
+}:
 
-with pkgs;
-
-stdenv.mkDerivation {
+stdenvNoCC.mkDerivation {
   name = "nixpkgs-lib-docs";
-  src = pkgs.lib.fileset.toSource {
+
+  src = lib.fileset.toSource {
     root = ../..;
     fileset = ../../lib;
   };
 
-  buildInputs = [ nixdoc nix ];
+  buildInputs = [
+    nixdoc
+    nix
+  ];
+
   installPhase = ''
     export NIX_STATE_DIR=$(mktemp -d)
     nix-instantiate --eval --strict --json ${./lib-function-locations.nix} \
       --arg nixpkgsPath "./." \
       --argstr revision ${nixpkgs.rev or "master"} \
-      --argstr libsetsJSON ${pkgs.lib.escapeShellArg (builtins.toJSON libsets)} \
+      --argstr libsetsJSON ${lib.escapeShellArg (builtins.toJSON libsets)} \
       > locations.json
 
     function docgen {
@@ -39,9 +127,16 @@ stdenv.mkDerivation {
     ```{=include=} sections auto-id-prefix=auto-generated
     EOF
 
-    ${lib.concatMapStrings ({ name, baseName ? name, description }: ''
-      docgen ${name} ${baseName} ${lib.escapeShellArg description}
-    '') libsets}
+    ${lib.concatMapStrings (
+      {
+        name,
+        baseName ? name,
+        description,
+      }:
+      ''
+        docgen ${name} ${baseName} ${lib.escapeShellArg description}
+      ''
+    ) libsets}
 
     echo '```' >> "$out/index.md"
   '';