fix: documentation.{man-db,mandoc} -> documentation.man.{man-db,mandoc}

nix/nixos-modules/useable.nix

@@ -28,20 +28,30 @@ in
 
 
     documentation = {
+
       enable = true;
       dev.enable = true;
       doc.enable = true;
       info.enable = true;
-      man.enable = true;
+
-      man.generateCaches = true;
+      man = {
+
+        enable = true;
+        generateCaches = true;
+
         man-db.enable = false; # see mandoc
+
         mandoc = {
           enable = true;
         };
+
+      };
+
       nixos = {
         enable = true;
         includeAllModules = true;
       };
+
     };