feat: nix nushell completions

Signed-off-by: jolheiser <john.olheiser@gmail.com>

flake.nix

@@ -8,7 +8,7 @@
     nixpkgs,
   }: let
     pkgs = nixpkgs.legacyPackages.x86_64-linux;
-    tmpl = pkgs.buildGoModule {
+    tmpl = pkgs.buildGoModule rec {
       pname = "tmpl";
       version = "0.4.0";
 
@@ -16,6 +16,13 @@
 
       vendorHash = "sha256-QNwzHC4fHLAhshOplKmMjRYa9sHNjBLdfBgANbs/iKk=";
 
+      ldflags = ["-s" "-w" "-X=go.jolheiser.com/tmpl/cmd.Version=${version}"];
+
+      postInstall = ''
+        mkdir -p $out/share
+        cp -vr ./contrib/tmpl-completions.nu $out/share/tmpl-completions.nu
+      '';
+
       meta = with pkgs.lib; {
         description = "";
         homepage = "https://git.jojodev.com/jolheiser/tmpl";