Update README.md

Author: KenChoi1992

README.md

@@ -118,7 +118,8 @@
 > 以下片断来自项目代码里的文件：example / cn.jpush.api.examples.PushExample
 
 ```Java
-    JPushClient jpushClient = new JPushClient(masterSecret, appKey, 3);
+    ClientConfig clientConfig = ClientConfig.getInstance();
+    JPushClient jpushClient = new JPushClient(masterSecret, appKey, null, clientConfig);
 
     // For push, all you need do is to build PushPayload object.
     PushPayload payload = buildPushObject_all_all_alert();