fix(guide): simplify directory structure

guide/english/csharp/linq/last-or-default/index.md

@@ -0,0 +1,24 @@
+---
+title: LastOrDefault
+---
+ # Any
+ Returns the last element in a sequence that satisfies a condition or a default value if no element is found
+ ### Signature
+```csharp
+Enumerable.LastOrDefault<TSource> Method (IEnumerable<TSource>, Func<TSource, Boolean>)
+```
+ ## Example
+```csharp
+var fruits = new List<Fruit>() {
+    new Fruit() { Id = 1, Name = "Orange",     Color = "Orange", Quantity: 3   },
+    new Fruit() { Id = 2, Name = "Strawberry", Color = "Red",    Quantity: 12  },
+    new Fruit() { Id = 3, Name = "Grape",      Color = "Purple", Quantity: 25  },
+    new Fruit() { Id = 4, Name = "Pineapple",  Color = "Yellow", Quantity: 1   },
+    new Fruit() { Id = 5, Name = "Apple",      Color = "Red",    Quantity: 5   },
+    new Fruit() { Id = 6, Name = "Mango",      Color = "Yellow", Quantity: 2   }
+};
+ // Returns the last fruit where the Color is Yellow
+var lastYellow = fruits.LastOrDefault(f => f.Color == "Yellow"); // Mango
+ // Returns the last fruit where the quantity is 20
+var lastQuantityOfTwenty = fruits.LastOrDefault(f => f.Quantity == 20); // null
+```