Fix prototypesource code

Author: sookim-1

Design-Patterns-CN.playground/Pages/Creational.xcplaygroundpage/Contents.swift

@@ -236,7 +236,7 @@ let screenTitle: String = Settings().currentTheme == .old ? "Itunes Connect" : "
 
 ### 示例：
 */
-struct MoonWorker {
+class MoonWorker {
 
     let name: String
     var health: Int = 100

Design-Patterns.playground/Pages/Creational.xcplaygroundpage/Contents.swift

@@ -241,7 +241,7 @@ This practise is particularly useful when the construction of a new object is in
 
 ### Example
 */
-struct MoonWorker {
+class MoonWorker {
 
     let name: String
     var health: Int = 100

Design-Patterns.playground/Pages/Creational.xcplaygroundpage/timeline.xctimeline

@@ -1054,7 +1054,7 @@ let screenTitle: String = Settings().currentTheme == .old ? "Itunes Connect" : "
 ### 示例：
 
 ```swift
-struct MoonWorker {
+class MoonWorker {
 
     let name: String
     var health: Int = 100

README-CN.md

@@ -6,7 +6,7 @@
 
 ### 示例：
 */
-struct MoonWorker {
+class MoonWorker {
 
     let name: String
     var health: Int = 100

source-cn/creational/prototype.swift

@@ -7,7 +7,7 @@ This practise is particularly useful when the construction of a new object is in
 
 ### Example
 */
-struct MoonWorker {
+class MoonWorker {
 
     let name: String
     var health: Int = 100