refactor(flake): update namespace and improve overlay structure

- Renamed namespace from "hello" to "cratedocs" for better clarity.
- Optimized overlay definitions and improved package structure resolution.
- Added `cratedocs-mcp` to overlays for streamlined integration.

flake.nix

@@ -5,34 +5,41 @@
   };
   outputs = { self, nixpkgs, rust-overlay, ... }:
     let
-      namespace = "hello";
+      namespace = "cratedocs";
       overlays = [ rust-overlay.overlays.default ];
       forEachSystem = systems: f: nixpkgs.lib.genAttrs systems f;
       forAllSystems = function:
         nixpkgs.lib.genAttrs nixpkgs.lib.systems.flakeExposed
-        (system: function (import nixpkgs { inherit system overlays; }));
-    in {
+          (system: function (import nixpkgs { inherit system overlays; }));
+    in
+    {
       packages =
         forAllSystems (pkgs: (self.overlays.default pkgs pkgs).${namespace});
       cross = forAllSystems (pkgs:
-        (forEachSystem (nixpkgs.lib.filter (sys: sys != pkgs.system)
-          nixpkgs.lib.systems.flakeExposed) (crossSystem:
+        (forEachSystem
+          (nixpkgs.lib.filter (sys: sys != pkgs.system)
+            nixpkgs.lib.systems.flakeExposed)
+          (crossSystem:
             let
               crossPkgs = import nixpkgs {
                 localSystem = pkgs.system;
                 inherit crossSystem;
               };
-            in (self.overlays.default crossPkgs crossPkgs).${namespace})));
+            in
+            (self.overlays.default crossPkgs crossPkgs).${namespace})));
       devShells =
         forAllSystems (pkgs: (self.overlays.default pkgs pkgs).devShells);
       formatter = forAllSystems (pkgs: pkgs.nixpkgs-fmt);
       overlays.default = final: prev:
-        let pkgs = final;
-        in {
+        let
+          pkgs = final;
+          cratedocs-mcp = pkgs.callPackage ./default.nix { };
+        in
+        {
           devShells.default = pkgs.callPackage ./shell.nix { };
           ${namespace} = {
-            hello = pkgs.callPackage ./default.nix { };
-            default = pkgs.callPackage ./default.nix { };
+            inherit cratedocs-mcp;
+            default = cratedocs-mcp;
           };
         };
     };