docs: 完善文档

Author: fudiwei

docs/WechatTenpayV3/FAQ_IISProblem.md

@@ -0,0 +1,37 @@
+## 常见问题：本地开发时正常，发布到 IIS 后请求抛出异常？
+
+---
+
+如果你遇到的异常信息如下：
+
+```
+Message:
+  Failed to sign request. Please see the inner exception for more details.
+
+StackTrace:
+  at SKIT.FlurlHttpClient.Wechat.TenpayV3.Interceptors.WechatTenpayRequestSigningInterceptor.BeforeCallAsync(HttpInterceptorContext context,   CancellationToken cancellationToken)
+  at SKIT.FlurlHttpClient.CommonClientBase.<>c__DisplayClass12_0.<<-ctor>b__1>d.MoveNext()
+  at Flurl.Http.FlurlClient.RaiseEventAsync(FlurlEventType eventType, FlurlCall call)
+  at Flurl.Http.FlurlClient.SendAsync(IFlurlRequest request, HttpCompletionOption completionOption, CancellationToken cancellationToken)
+  at SKIT.FlurlHttpClient.CommonClientBase.SendFlurlRequestAsync(IFlurlRequest flurlRequest, HttpContent httpContent, CancellationToken   cancellationToken)
+  at SKIT.FlurlHttpClient.CommonClientBase.SendFlurlRequestAsJsonAsync(IFlurlRequest flurlRequest, Object data, CancellationToken cancellationToken)
+  at SKIT.FlurlHttpClient.Wechat.TenpayV3.WechatTenpayClient.SendFlurlRequestAsJsonAsync[T](IFlurlRequest flurlRequest, Object data, CancellationToken cancellationToken)
+
+InnerException:
+  System.Security.Cryptography.CryptographicException: 系统找不到指定的文件。
+  Internal.Cryptography.CryptoThrowHelper+WindowsCryptographicException: 系统找不到指定的文件。
+  at System.Security.Cryptography.CngKeyLite.ImportKeyBlob(String blobType, ReadOnlySpan1 keyBlob, Boolean encrypted, ReadOnlySpan1 password)
+  at System.Security.Cryptography.CngPkcs8.ImportPkcs8(ReadOnlySpan1 keyBlob) at System.Security.Cryptography.CngPkcs8.ImportPkcs8PrivateKey  (ReadOnlySpan1 source, Int32& bytesRead)
+  at System.Security.Cryptography.RSAImplementation.RSACng.ImportPkcs8PrivateKey(ReadOnlySpan`1 source, Int32& bytesRead)
+  at SKIT.FlurlHttpClient.Wechat.TenpayV3.Utilities.RSAUtility.SignWithSHA256(Byte[] privateKeyBytes, Byte[] messageBytes)
+  at SKIT.FlurlHttpClient.Wechat.TenpayV3.Utilities.RSAUtility.SignWithSHA256(String privateKeyPem, String messageData)
+  at SKIT.FlurlHttpClient.Wechat.TenpayV3.Interceptors.WechatTenpayRequestSigningInterceptor.BeforeCallAsync(HttpInterceptorContext context, CancellationToken cancellationToken)
+```
+
+请检查你的 IIS 应用程序池设置中是否开启了「用户加载配置文件」选项。如果没有，请尝试勾选后重启服务。
+
+---
+
+> 参考链接：
+>
+> https://stackoverflow.com/questions/17840825

docs/WechatTenpayV3/README.md

@@ -136,6 +136,12 @@ else
 
 ---
 
+## 常见问题
+
+-   [本地开发时正常，发布到 IIS 后请求抛出异常？](./FAQ_IISProblem.md)
+
+---
+
 ## 示例项目
 
 为方便开发者快速掌握本库的使用方法，这里提供一个示例项目以供参考。