fix(guide): simplify directory structure

guide/chinese/csharp/nested-if-statement/index.md

@@ -0,0 +1,25 @@
+---
+title: Nested If Statement
+localeTitle: 嵌套If语句
+---
+# 嵌套If语句
+
+在创建if语句时使用嵌套If语句，您需要辅助验证点或if语句。
+```
+int Price = 100; 
+ int Quantity = 20; 
+ 
+ if (Price == 100) 
+ { 
+  if (Quantity == 20) 
+  { 
+    Console.WriteLine("Price of an item is 200, and we have 20 in quantity."); 
+  } 
+ } 
+```
+
+因此，由于我们预定的价格和数量，输出将是：
+```
+Price of an item is 200, and we have 20 in quantity. 
+
+```