docs/modules: add main entrypoint

docs/lib/default.nix

@@ -11,7 +11,7 @@ let
   menuConfiguration = lib.evalModules {
     modules = [
       pageSpecs
-      ../modules/menu.nix
+      ../modules
     ];
   };
   cfg = menuConfiguration.config;

docs/modules/default.nix

@@ -0,0 +1,12 @@
+{ lib, ... }:
+let
+  categoryType = lib.types.submoduleWith {
+    modules = [ ./category.nix ];
+  };
+in
+{
+  freeformType = lib.types.attrsOf categoryType;
+  imports = [
+    ./menu.nix
+  ];
+}

docs/modules/menu.nix

@@ -5,15 +5,9 @@
   ...
 }:
 let
-  categoryType = lib.types.submoduleWith {
-    modules = [ ./category.nix ];
-  };
-
   categories = removeAttrs config (builtins.attrNames options);
 in
 {
-  freeformType = lib.types.attrsOf categoryType;
-
   options._menu = {
     text = lib.mkOption {
       type = lib.types.str;