update zh-cn/application-dev/reference/apis/js-apis-bluetooth.md.

添加删掉的三级标题
Signed-off-by: Nlverpeng <lverpeng118@163.com>

zh-cn/application-dev/reference/apis/js-apis-bluetooth.md

@@ -1144,7 +1144,7 @@ let a2dpSrc = bluetooth.getProfile(bluetooth.ProfileId.PROFILE_A2DP_SOURCE);
 
 ## bluetooth.BLE
 
-createGattServer<sup>(deprecated)</sup>
+### createGattServer<sup>(deprecated)</sup>
 
 createGattServer(): GattServer
 
@@ -1168,7 +1168,7 @@ let gattServer = bluetooth.BLE.createGattServer();
 ```
 
 
-createGattClientDevice<sup>(deprecated)</sup>
+### createGattClientDevice<sup>(deprecated)</sup>
 
 createGattClientDevice(deviceId: string): GattClientDevice
 
@@ -1198,7 +1198,7 @@ let device = bluetooth.BLE.createGattClientDevice('XX:XX:XX:XX:XX:XX');
 ```
 
 
-getConnectedBLEDevices<sup>(deprecated)</sup>
+### getConnectedBLEDevices<sup>(deprecated)</sup>
 
 getConnectedBLEDevices(): Array&lt;string&gt;
 
@@ -1224,7 +1224,7 @@ let result = bluetooth.BLE.getConnectedBLEDevices();
 ```
 
 
-startBLEScan<sup>(deprecated)</sup>
+### startBLEScan<sup>(deprecated)</sup>
 
 startBLEScan(filters: Array&lt;ScanFilter&gt;, options?: ScanOptions): void
 
@@ -1270,7 +1270,7 @@ bluetooth.BLE.startBLEScan(
 ```
 
 
-stopBLEScan<sup>(deprecated)</sup>
+### stopBLEScan<sup>(deprecated)</sup>
 
 stopBLEScan(): void
 
@@ -1294,7 +1294,7 @@ bluetooth.BLE.stopBLEScan();
 ```
 
 
-on('BLEDeviceFind')<sup>(deprecated)</sup>
+### on('BLEDeviceFind')<sup>(deprecated)</sup>
 
 on(type: "BLEDeviceFind", callback: Callback&lt;Array&lt;ScanResult&gt;&gt;): void
 
@@ -1328,7 +1328,7 @@ bluetooth.BLE.on('BLEDeviceFind', onReceiveEvent);
 ```
 
 
-off('BLEDeviceFind')<sup>(deprecated)</sup>
+### off('BLEDeviceFind')<sup>(deprecated)</sup>
 
 off(type: "BLEDeviceFind", callback?: Callback&lt;Array&lt;ScanResult&gt;&gt;): void