Move nix files to /contrib

Author: ryuheechul

.gitignore

@@ -7,5 +7,3 @@ release
 .env
 .envrc
 src-snapshot/
-# for `nix build`
-result

contrib/.gitignore

@@ -0,0 +1,2 @@
+# for `nix build`
+result

default.nix renamed to contrib/default.nix

@@ -18,8 +18,8 @@
       rec {
         packages.src-cli = with pkgs; buildGoModule.override { go = pkgs.go_1_19; } {
           pname = "src-cli";
-          version = self.shortRev or "dirty";;
-          src = ./.;
+          version = self.shortRev or "dirty";
+          src = ../.;
 
           subPackages = [ "cmd/src" ];