Fix copy (#6)

Author: shad-k

exercises/03.auth-info/02.problem.error/README.mdx

@@ -4,7 +4,7 @@
 
 👨‍💼 When clients provide an authentication token that turns out to be invalid or expired, they need clear feedback about what went wrong. Without proper error messaging, users might think the service is broken or get confused about why their request failed.
 
-The current error response doesn't distinguish between "no token provided" and "invalid token provided." This makes it harder for clients to provide helpful guidance to clients about what they need to do next.
+The current error response doesn't distinguish between "no token provided" and "invalid token provided." This makes it harder for clients to provide helpful guidance to users about what they need to do next.
 
 ```
 // When no Authorization header is present: