Add screenshots in the README.md (feedback from cloud-barista#1960)

Add screenshots of using a generated encryption key file for the credential file

README.md

@@ -217,15 +217,23 @@ To provisioning multi-cloud infrastructures with CB-TB, it is necessary to regis
     ```bash
     init/encCredential.sh
     ```
+    After running the command, you can choose to enter a custom password or let the system generate a random key for you.
+    If you decide to enter a custom password:
     ![Image](https://github.com/user-attachments/assets/8f051ce8-9282-4e6d-a8ae-af5c831622c7)
+    If you choose to let the system generate a random key:
+    ![Image](https://github.com/user-attachments/assets/807511ee-05d9-481e-a191-d1aad2e9aeb2)
 
   If you need to update your credentials, decrypt the encrypted file using `decCredential.sh`, make the necessary changes to `credentials.yaml`, and then re-encrypt it.
 
   - Decrypting Credentials
     ```bash
     init/decCredential.sh
     ```
+    If you entered a custom password, please use the same password to decrypt the file:
     ![Image](https://github.com/user-attachments/assets/600921fb-cdff-4313-ae4d-266ddd31809b)
+    If you generated a random key, enter it to decrypt the file:
+    ![Image](https://github.com/user-attachments/assets/2bb029a4-8dd9-4e1a-8cad-af70ca72e9fd)
+
 
 - (INIT) Register all multi-cloud connection information and common resources