[이벤트 위임] 과제2 문제 번역 - line 13(#1311)

Author: YOOJS1205

2-ui/2-events/03-event-delegation/2-sliding-tree/task.md

@@ -10,5 +10,5 @@ Create a tree that shows/hides node children on click:
 
 Requirements:
 
-- Only one event handler (use delegation)
+- 단 하나의 이벤트 핸들러(이벤트 위임 사용하기)
 - A click outside the node title (on an empty space) should not do anything.