update docs

Signed-off-by: Nshawn_he <shawn.he@huawei.com>

en/readme/ai.md

@@ -321,7 +321,7 @@ The AI subsystem is the part of OpenHarmony that provides native distributed AI
     }
     ```
 
-4.  Develop a sample application.  For details, see the [\keyword spotting demo\](https://gitee.com/openharmony/applications_sample_camera/tree/master/ai).
+4.  Develop a sample application. For details, see the [keyword spotting demo](https://gitee.com/openharmony/applications_sample_camera/tree/master/ai).
 
     Directory: //applications/sample/camera/ai/asr/keyword\_spotting