refator: mart main -> mart Main

Author: JBumLee

src/main/java/org/nhnacademy/leejungbum/mart2/mart/main.java renamed to src/main/java/org/nhnacademy/leejungbum/mart2/mart/Main.java

@@ -1,6 +1,6 @@
 package org.nhnacademy.leejungbum.mart2.mart;
 
-public class main {
+public class Main {
     public static void main(String[] args) {
         Store store = new Store(5);
         Buyer buyer[] = new Buyer[10];