chore: Optimize flake.nix file by removing unused code and dependencies

- Removed unused metadata, comment lines, code, and dependencies in `flake.nix`
- Removed unused devShells and defaultPackage in `flake.nix`

flake.nix

 {
  description = "docman is a document management tool";
 
-  # Nixpkgs / NixOS version to use.
-  
   inputs = {
     nixpkgs.url = "nixpkgs/nixos-23.05";
     versionTool.url = "https://gitlab.schukai.com/oss/utilities/version/-/archive/0.5.0/version-0.5.0.tar.gz";
@@ -11,86 +9,49 @@
   outputs = { self, nixpkgs, versionTool, ... }:
     let
 
-      # to work with older version of flakes
       lastModifiedDate = self.lastModifiedDate or self.lastModified or "19700101";
 
       rootPath = ./.;
 
-      # System types to support.
       supportedSystems = [ "x86_64-linux" "x86_64-darwin" "aarch64-linux" "aarch64-darwin" ];
 
-      # Helper function to generate an attrset '{ x86_64-linux = f "x86_64-linux"; ... }'.
       forAllSystems = nixpkgs.lib.genAttrs supportedSystems;
 
-      # Nixpkgs instantiated for supported system types.
       nixpkgsFor = forAllSystems (system: import nixpkgs { inherit system; });
       
       pkgs = import nixpkgs { system = "x86_64-linux"; };
       
-#      versionTool = pkgs.fetchzip {
-#        url = "https://gitlab.schukai.com/oss/utilities/version/-/archive/0.5.0/version-0.5.0.tar.gz";
-#        # You'll need to provide the correct hash here.
-#        sha256 = "sha256-jzixQKFFW4oxO0S4GYqbkFCXzhBd6com6Z9+MtVKakU=";
-#      };   
-   
-
     in
     {
 
-      # Provide some binary packages for selected system types.
+
       packages = forAllSystems (system:
         let
           pkgs = nixpkgsFor.${system};
           
-          # Build the versionTool for the current system.
           versionToolPackage = versionTool.defaultPackage.${system};
-
-#          versionAndBuild = pkgs.runCommand "get-version-and-build" {} ''
-#            ${versionToolPackage}/bin/version print --git > $out.version
-#            ${versionToolPackage}/bin/version build > $out.build
-#          '';
-#
-#          version = builtins.trace (builtins.readFile "${versionAndBuild}.version";
-#          build = builtins.readFile "${versionAndBuild}.build";
-
-          versionAndBuild = pkgs.runCommand "get-version-and-build" {
-              outputFiles = [ "version" "build" ];
-          } ''
-              ${versionToolPackage}/bin/version print --git > $out/version
-              ${versionToolPackage}/bin/version build > $out/build
-          '';           
           
-          version = builtins.trace (builtins.readFile "${versionAndBuild}.version") "Reading version";
-          build = builtins.trace (builtins.readFile "${versionAndBuild}.build") "Reading build";
+        versionAndBuild = pkgs.runCommand "get-version-and-build" {
+            outputFiles = [ "version" "build" ];
+        } ''
+            ${versionToolPackage}/bin/version print --git > $out/version
+            ${versionToolPackage}/bin/version build > $out/build
+        '';
+        
+        version = builtins.trace (builtins.readFile "${versionAndBuild}/version") "Reading version";
+        build = builtins.trace (builtins.readFile "${versionAndBuild}/build") "Reading build";
+          
+          
+          
           
         in
         {
           docman = pkgs.buildGoModule {
           
-           buildPhase = ''
-              version=$(${versionTool}/bin/version print --git)
-              build=$(${versionTool}/bin/version build)
-              
-              go build -ldflags "-X 'gitlab.schukai.com/oss/utilities/documentation-manager/release.version=$version' -X 'gitlab.schukai.com/oss/utilities/documentation-manager/release.build=$build'"
-            '';
-          
             name = "docman";
-            # In 'nix develop', we don't need a copy of the source tree
-            # in the Nix store.
             src = ././source;
             version = "${version}";
 
-            # This hash locks the dependencies of this package. It is
-            # necessary because of how Go requires network access to resolve
-            # VCS.  See https://www.tweag.io/blog/2021-03-04-gomod2nix/ for
-            # details. Normally one can build with a fake sha256 and rely on native Go
-            # mechanisms to tell you what the hash should be or determine what
-            # it should be "out-of-band" with other tooling (eg. gomod2nix).
-            # To begin with it is recommended to set this, but one must
-            # remeber to bump this hash when your dependencies change.
-            #vendorSha256 = pkgs.lib.fakeSha256;
-
-            #vendorSha256 = "sha256-XdB+u94Rqsb29jVs4miyOq1NEYaVJHWFXg6QebFJzNQ=";
             vendorSha256 = "sha256-81IBG8H1jsYKD+tmFeCpAWFdz6cuQDt9r+FV56xboBU=";
             
             ldflags = [
@@ -109,7 +70,6 @@
           };
         });
       
-      # Add dependencies that are only needed for development
       devShells = forAllSystems (system:
         let 
           pkgs = nixpkgsFor.${system};
@@ -120,9 +80,7 @@
           };
         });
 
-      # The default package for 'nix build'. This makes sense if the
-      # flake provides only one package or there is a clear "main"
-      # package.
+
       defaultPackage = forAllSystems (system: self.packages.${system}.docman);
     };
 }