update doc

docs/how-to-connect/casdoor-authenticator-app.md

@@ -13,6 +13,10 @@ In addition to client-side functionality, Casdoor also offers server-side manage
 
 Whether you are a developer, an administrator, or an end-user, the Casdoor Authenticator App ensures a seamless, secure, and flexible way to manage your two-factor authentication.
 
+| Android App | iOS App |
+| ----------- | ------- |
+| ![android](/img/casdoor-authenticator-app/android.png) | ![ios](/img/casdoor-authenticator-app/ios.png) |
+
 ## What is TOTP?
 
 TOTP stands for Time-based One-Time Passwords and is a common form of two-factor authentication (2FA). Unique numeric passwords are generated with a standardized [algorithm](https://tools.ietf.org/html/rfc6238) that uses the current time as an input. The time-based passwords are available offline and provide user-friendly, increased account security when used as a second factor.
@@ -21,9 +25,12 @@ TOTP stands for Time-based One-Time Passwords and is a common form of two-factor
 
 ### Step 0: Install the Casdoor Authenticator App
 
-Right now, the Casdoor Authenticator App is available for Android devices. You can download the app from the official GitHub repository: [Casdoor Authenticator App](https://github.com/casdoor/casdoor-app/releases/latest) and install it on your Android device.
+The Casdoor Authenticator App is currently available for Android devices. You can download the app from the following sources:
+
+1. Official GitHub Releases: [Casdoor Authenticator App Latest Release](https://github.com/casdoor/casdoor-app/releases/latest)
+2. Source Code: [Casdoor Authenticator App GitHub Repository](https://github.com/casdoor/casdoor-app)
 
-Alternatively, you can build the app from the source code available on GitHub check this for reference [Building from Source](https://github.com/casdoor/casdoor-app#building-from-source).
+For developers interested in building the app from source, you can find the source code and build instructions in the [Casdoor App GitHub Repository](https://github.com/casdoor/casdoor-app#building-from-source).
 
 ### Step 1: Enable Totp Account storage in Casdoor Server (Optional)
 
@@ -52,3 +59,5 @@ Select the "Transfer Accounts" option in the menu of Google Authenticator and ch
 ### Step 2: Import TOTP data to the Casdoor Authenticator App
 
 In the Casdoor Authenticator App, scan the QR code generated by Google Authenticator to import your TOTP data. The app will automatically add the accounts to your Casdoor Authenticator App, allowing you to manage your TOTP codes securely.
+
+![Import TOTP data](/img/casdoor-authenticator-app/import-totp.gif)