Revise "Enforce authentication #nm2"

Clarified the explanation of `default` user authentication and updated example usage for better understanding.

Author: TropicolX

stage_descriptions/auth-07-nm2.md

@@ -1,15 +1,16 @@
 In this stage, you'll add support for enforcing authentication for the `default` user.
 
-### Enforcing `default` user authentication
+### Enforcing `default` User Authentication
 
-By default, every new connection is automatically authenticated as the `default` user. This is because the `nopass` flag is set for the `default` user from the start. However, after clearing this flag (by setting a password for the `default` user), new connections are not automatically authenticated as the `default` user. Connections which have already been authenticated will remain authenticated.
+When you create a new connection, it is automatically authenticated as the `default` user. This happens because the `nopass` flag is set for the `default` user from the start.
 
-Example usage:
+Once you set a password for the `default` user, new connections will no longer be automatically authenticated. However, any connections that were already authenticated will stay logged in.
+
+For example:
 
 ```bash
 # Client 1
-$ redis-cli
-> ACL SETUSER default >password
+$ redis-cli ACL SETUSER default >password
 OK
 
 # This connection remains authenticated as the default user
@@ -18,11 +19,12 @@ OK
 
 # Client 2
 # This connection is not authenticated
-$ redis-cli
-> ACL WHOAMI
+$ redis-cli ACL WHOAMI
 (error) NOAUTH Authentication required.
 ```
 
+When an unauthenticated connection tries to execute a command, return the simple error: `NOAUTH Authentication required.`
+
 ### Tests
 
 The tester will execute your program like this:
@@ -31,7 +33,7 @@ The tester will execute your program like this:
 $ ./your_program.sh
 ```
 
-It'll then send commands to two different clients.
+It will then send commands to two different clients:
 
 ```bash
 # Client 1
@@ -51,9 +53,6 @@ $ redis-cli
 (error) NOAUTH Authentication required.
 ```
 
-The tester will validate the following:
-
-1. The first client (Client 1) is still authenticated as the `default` user.
-
-2. A second client (Client 2) receives a `NOAUTH` error when attempting to execute commands without authentication.
-    - This is because after we set the password for the `default` user, the `nopass` flag is also cleared. This disables auto-authentication of new users as the `default` user.
+The tester will verify that:
+- Client 1 can still execute commands and remains authenticated as the `default` user.
+- Client 2 receives a `NOAUTH` error when trying to execute commands without authentication.