Fix: IE10 bug - DOCTYPE, IE=Edge, let -> var

src/web/module/maestro_section_add_player.html

@@ -17,8 +17,8 @@ $(document).ready(function() {
 });
 
 function addPlayer() {
-	let playerName = $("#player_name").val();
-	let enterCode = $("#entercode").val();
+	var playerName = $("#player_name").val();
+	var enterCode = $("#entercode").val();
 
 	if(playerName.length === 0) {
 		onErrorPlayerName("학생 이름을 입력하세요.");