!11338 Example of modifying XML

Merge pull request !11338 from 小马奔腾/master

en/application-dev/reference/apis/js-apis-xml.md

@@ -59,7 +59,9 @@ Sets an attribute.
 let arrayBuffer = new ArrayBuffer(1024);
 let bufView = new DataView(arrayBuffer);
 let thatSer = new xml.XmlSerializer(bufView);
+thatSer.startElement("note");
 thatSer.setAttributes("importance", "high");
+thatSer.endElement();
 ```
 
 

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

@@ -58,7 +58,9 @@ setAttributes(name: string, value: string): void
 let arrayBuffer = new ArrayBuffer(1024);
 let bufView = new DataView(arrayBuffer);
 let thatSer = new xml.XmlSerializer(bufView);
+thatSer.startElement("note");
 thatSer.setAttributes("importance", "high"); 
+thatSer.endElement(); 
 ```