Rename readme.md to README.MD

Extensions/FreeSql.Extensions.JsonMap/README.MD

@@ -0,0 +1,25 @@
+[中文](README.zh-CN.MD) | **English**
+
+FreeSql extension package, map *ValueObject* to `typeof(string)`, install the extension package:
+
+> dotnet add package FreeSql.Extensions.JsonMap
+
+```csharp
+fsql.UseJsonMap(); //Turn on function
+
+class TestConfig
+{
+    public int clicks { get; set; }
+    public string title { get; set; }
+}
+
+[Table(Name = "sysconfig")]
+public class S_SysConfig<T>
+{
+    [Column(IsPrimary = true)]
+    public string Name { get; set; }
+
+    [JsonMap]
+    public T Config { get; set; }
+}
+```