更新RM

xxl-job-core/src/main/java/com/xxl/job/core/handler/IJobHandler.java

 
 
 	/**
-	 * execute handler
+	 * execute handler, invoked when executor receives a scheduling request
 	 *
 	 * @param param
 	 * @return
 
 
 	/**
-	 * init handler
+	 * init handler, invoked when JobThread init
 	 */
 	public void init() {
 		// TODO
 
 
 	/**
-	 * destroy handler
+	 * destroy handler, invoked when JobThread destroy
 	 */
 	public void destroy() {
 		// TODO