update docs against 7967

Signed-off-by: Nwusongqing <wusongqing@huawei.com>

en/application-dev/ability/stage-serviceextension.md

@@ -39,33 +39,36 @@ OpenHarmony does not support creation of a Service Extension ability for third-p
    ```
 
 
-2. Customize a class that inherits from **ServiceExtensionAbility** in the .ts file in the directory where the Service Extension ability is defined and override the lifecycle callbacks of the base class. The code sample is as follows:
+2. Customize a class that inherits from **ServiceExtensionAbility** in the .ts file in the directory where the Service Extension ability is defined (**entry\src\main\ets\ServiceExtAbility\ServiceExtAbility.ts** by default) and override the lifecycle callbacks of the base class. The code sample is as follows:
 
     ```js
+    import ServiceExtensionAbility from '@ohos.application.ServiceExtensionAbility'
     import rpc from '@ohos.rpc'
+
     class StubTest extends rpc.RemoteObject {
-      constructor(des) {
+        constructor(des) {
             super(des);
-      }
-      onRemoteRequest(code, data, reply, option) {
-      }
+        }
+        onRemoteRequest(code, data, reply, option) {
+        }
     }
-    
-    class ServiceExt extends ServiceExtensionAbility {
-        console.log('onCreate, want:' + want.abilityName);
-      }
-      onRequest(want, startId) {
-        console.log('onRequest, want:' + want.abilityName);
-      }
-      onConnect(want) {
-        console.log('onConnect , want:' + want.abilityName);
-        return new StubTest("test");
-      }
-      onDisconnect(want) {
-        console.log('onDisconnect, want:' + want.abilityName);
-      }
-      onDestroy() {
-        console.log('onDestroy');
-      }
+
+    class ServiceExtAbility extends ServiceExtensionAbility {
+        onCreate(want) {
+            console.log('onCreate, want:' + want.abilityName);
+        }
+        onRequest(want, startId) {
+            console.log('onRequest, want:' + want.abilityName);
+        }
+        onConnect(want) {
+            console.log('onConnect , want:' + want.abilityName);
+            return new StubTest("test");
+        }
+        onDisconnect(want) {
+            console.log('onDisconnect, want:' + want.abilityName);
+        }
+        onDestroy() {
+            console.log('onDestroy');
+        }
     }
-    ```
+    ```
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