docs: use pkgsDoc to build helpers

docs/default.nix

@@ -1,4 +1,4 @@
-{ helpers, pkgs }:
+{ getHelpers, pkgs }:
 let
   # Extend nixpkg's lib, so that we can handle recursive leaf types such as `either`
   lib = pkgs.lib.extend (
@@ -32,6 +32,8 @@ let
     inherit lib;
   };
 
+  helpers = getHelpers pkgsDoc false;
+
   nixvimPath = toString ./..;
 
   gitHubDeclaration = user: repo: branch: subpath: {

flake-modules/packages.nix

@@ -1,14 +1,10 @@
+{ getHelpers, ... }:
 {
   perSystem =
-    {
-      pkgsUnfree,
-      config,
-      helpers,
-      ...
-    }:
+    { pkgsUnfree, config, ... }:
     {
       packages = import ../docs {
-        inherit helpers;
+        inherit getHelpers;
         # Building the docs evaluates each plugin's default package, some of which are unfree
         pkgs = pkgsUnfree;
       };