update docs/api/media/background-audio-manager.md.

docs/api/media/background-audio-manager.md

@@ -58,11 +58,11 @@ errCode 说明
 **示例**
 
 ```javascript
-const bgAudioMannager = uni.getBackgroundAudioManager();
-bgAudioMannager.title = '致爱丽丝';
-bgAudioMannager.singer = '暂无';
-bgAudioMannager.coverImgUrl = 'https://bjetxgzv.cdn.bspapp.com/VKCEYUGU-uni-app-doc/7fbf26a0-4f4a-11eb-b680-7980c8a877b8.png';
-bgAudioMannager.src = 'https://bjetxgzv.cdn.bspapp.com/VKCEYUGU-hello-uniapp/2cc220e0-c27a-11ea-9dfb-6da8e309e0d8.mp3';
+const bgAudioManager = uni.getBackgroundAudioManager();
+bgAudioManager.title = '致爱丽丝';
+bgAudioManager.singer = '暂无';
+bgAudioManager.coverImgUrl = 'https://bjetxgzv.cdn.bspapp.com/VKCEYUGU-uni-app-doc/7fbf26a0-4f4a-11eb-b680-7980c8a877b8.png';
+bgAudioManager.src = 'https://bjetxgzv.cdn.bspapp.com/VKCEYUGU-hello-uniapp/2cc220e0-c27a-11ea-9dfb-6da8e309e0d8.mp3';
 ```