Add English comments for JsonMap extension package.

Extensions/FreeSql.Extensions.JsonMap/DataAnnotations/JsonMapAttribute.cs

@@ -1,13 +1,11 @@
 using System;
-using System.Linq;
 
+// ReSharper disable once CheckNamespace
 namespace FreeSql.DataAnnotations
 {
-
     /// <summary>
-    /// 当实体类属性为【对象】时，以JSON形式映射存储
+    /// When the entity class property is <see cref="object"/>, map storage in JSON format. <br />
+    /// 当实体类属性为【对象】时，以 JSON 形式映射存储
     /// </summary>
-    public class JsonMapAttribute : Attribute
-    {
-    }
-}
+    public class JsonMapAttribute : Attribute { }
+}