doc: Update README.md

Author: jaywcjlove

README.md

@@ -12,6 +12,7 @@
   ✦ My [macOS/iOS](https://wangchujiang.com/#app) application ✦
 
   <p style="display: inline_block">
+    <a target="_blank" href="https://wangchujiang.com/file-sentinel/" title="FileSentinel for macOS"><img align="center" alt="FileSentinel" height="52" width="52" src="https://github.com/user-attachments/assets/28bce2cc-290e-45bf-9068-585ff6ecafe9"></a>
     <a target="_blank" href="https://wangchujiang.com/focus-cursor/" title="FocusCursor for macOS"><img align="center" alt="FocusCursor" height="52" width="52" src="https://github.com/user-attachments/assets/d543668a-737b-4853-a6bb-eaa269e69836"></a>
     <a target="_blank" href="https://wangchujiang.com/videoer/" title="Videoer for macOS"><img align="center" alt="Videoer" height="52" width="52" src="https://github.com/user-attachments/assets/12c02a7a-109e-4048-91f4-ab2dfd1e264e"></a>
     <a target="_blank" href="https://wangchujiang.com/key-clicker/" title="KeyClicker for macOS"><img align="center" alt="KeyClicker" height="50" width="50" src="https://github.com/user-attachments/assets/5a19fcb9-cb81-4855-b4ea-31c604d9612a"></a>