docs: 完善文档

docs/WechatTenpayV3/Advanced_Extensions.md

@@ -0,0 +1,51 @@
+## 如何扩展额外的 API？
+
+---
+
+如果有某些接口本库尚未支持，你可按照下面的示例自行扩展：
+
+```csharp
+/* 继承 WechatTenpayRequest 实现自定义请求类 */
+public class MyFakeRequest : WechatTenpayRequest
+{
+    [Newtonsoft.Json.JsonProperty("my_fake_props")]
+    [System.Text.Json.Serialization.JsonPropertyName("my_fake_props")]
+    public string MyFakeProps { get; set; }
+}
+
+/* 继承 WechatTenpayResponse 实现自定义响应类 */
+public class MyFakeResponse : WechatTenpayResponse
+{
+    [Newtonsoft.Json.JsonProperty("my_fake_props")]
+    [System.Text.Json.Serialization.JsonPropertyName("my_fake_props")]
+    public string MyFakeProps { get; set; }
+}
+
+/* 扩展 WechatTenpayClient 方法 */
+public static class MyFakeClientExtensions
+{
+    public static async Task<MyFakeResponse> ExecuteMyFakeAsync(this WechatTenpayClient client, MyFakeRequest request, CancellationToken cancellationToken = default)
+    {
+        if (client is null) throw new ArgumentNullException(nameof(client));
+        if (request is null) throw new ArgumentNullException(nameof(request));
+
+        IFlurlRequest flurlReq = client
+            .CreateRequest(request, HttpMethod.Post, "my-fake-url")
+            .SetQueryParam("access_token", request.AccessToken);
+
+        return await client.SendRequestWithJsonAsync<MyFakeResponse>(flurlReq, request, cancellationToken);
+    }
+}
+```
+
+同样的，你也可自行扩展回调通知事件的敏感数据模型：
+
+```csharp
+/* 实现自定义的 JSON 格式的回调通知事件敏感数据 */
+public class MyFakeEvent : WechatTenpayEvent.Types.IDecryptedResource
+{
+    [Newtonsoft.Json.JsonProperty("my_fake_props")]
+    [System.Text.Json.Serialization.JsonPropertyName("my_fake_props")]
+    public string MyFakeProps { get; set; }
+}
+```

docs/WechatTenpayV3/README.md

@@ -147,3 +147,5 @@ else
 -   [如何解密回调通知事件中的敏感数据？](./Advanced_EventDataDecryption.md)
 
 -   [如何生成客户端调起支付时所需的参数及签名？](./Advanced_Payment.md)
+
+-   [如何扩展额外的 API？](./Advanced_Extensions.md)