chore: fix wrong code on README.md

Author: canermastan

README.md

@@ -159,9 +159,9 @@ public class UserController {
         Optional<User> user = userService.findByEmail(email);
 
         if (user.isPresent()) {
-            return Response.json(Map.of("user", user.get()));
+            return Response.json(JSON.of("user", user.get()));
         } else {
-            return Response.json(Map.of("error", "User not found")).status(404);
+            return Response.json(JSON.of("error", "User not found")).status(404);
         }
     }
 }
@@ -368,4 +368,4 @@ No contribution is too small, and we're happy to help newcomers get started! 
 
 ## License
 
-MIT License 
+MIT License