Fix incorrect comments

Author: rj@pop

src/network-services-pentesting/pentesting-web/nextjs.md

@@ -1015,8 +1015,8 @@ Manage sensitive information like API keys and database credentials securely wit
 
 module.exports = {
   env: {
-    SECRET_API_KEY: process.env.SECRET_API_KEY, // Exposed to the client
-    NEXT_PUBLIC_API_URL: process.env.NEXT_PUBLIC_API_URL, // Correctly prefixed for client
+    SECRET_API_KEY: process.env.SECRET_API_KEY, // Not exposed to the client
+    NEXT_PUBLIC_API_URL: process.env.NEXT_PUBLIC_API_URL, // Correctly prefixed for exposure to client
   },
 }
 ```