Updated readme and added new sample project

samples/ReadmeSample/Extensions/UserExtensions.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using EntityFrameworkCore.Projections;
+using ReadmeSample.Entities;
+
+namespace ReadmeSample.Extensions
+{
+    public static class UserExtensions
+    {
+        [Projectable]
+        public static Order GetMostRecentOrderForUser(this User user, DateTime? cutoffDate)
+            => user.Orders.Where(x => x.CreatedDate >= cutoffDate).OrderByDescending(x => x.CreatedDate).FirstOrDefault();
+    }
+}