ADDED markdown viewer and python-dotenv to shell

shell.nix

@@ -4,8 +4,14 @@
 with pkgs;
 pkgs.mkShell {
     nativeBuildInputs = [
+        inlyne # markdown viewer
+
         # Python development environment
         (python3.withPackages(ps: with ps; [
+            # For SDK configuration
+            python-dotenv
+
+            # HTTP client
             requests
         ]))
     ];