Update README.md

Author: Dmitry Panyushkin

README.md

@@ -1,2 +1,69 @@
 # AutoMapper.ExtendedConverters
-AutoMapper.ExtendedConverters is a small set of useful AutoMapper custom Type Converters
+AutoMapper.ExtendedConverters is a small set of useful AutoMapper custom Type Converters
+
+```cs
+using System.Diagnostics;
+using System.Linq;
+using AutoMapper;
+using AutoMapper.ExtendedConverters;
+
+class Model
+{
+    public int Id { get; set; }
+    public string Text { get; set; }
+}
+
+class Entity
+{
+    public int Id { get; set; }
+    public string Text { get; set; }
+}
+
+class Program
+{
+    static IMapper Mapper;
+    
+    static void Configure()
+    {
+        var config = new MapperConfiguration(cfg =>
+        {
+            cfg.CreateMap<Model, Entity>();
+            // create custom mapper for lists
+            cfg.CreateMap<List<Model>, List<Entity>>()
+                // configure 'Id' property selectors for Model and Entity
+                .UsingListConverter(m => m.Id, e => e.Id);
+        });
+        
+        Mapper = config.CreateMapper();
+    }
+    
+    static void Main()
+    {
+        // values from Server
+        var dest = new List<Entity>
+        {
+            new Entity { Id = 1, Text = "a" },
+            new Entity { Id = 2, Text = "b" },
+        };
+        // values from Client
+        var src = new List<Model>
+        {
+            new Model { Id = 1, Text = "A" },
+            new Model { Id = 3, Text = "C" },
+        };
+        
+        List<Entity> res = Mapper.Map(src, dest);
+        
+        // now res is equivalent to
+        new List<Entity>
+        {
+            // Entity with Id == 1 is updated
+            new Entity { Id = 1, Text = "A" },
+            // Entity with Id == 2 is removed
+            // ...
+            // Entity with Id == 3 is added
+            new Entity { Id = 3, Text = "C" },
+        }
+    }
+}
+```