documents http code

Author: ChocoLZS

content/en/docs/hertz/faq/_index.md

@@ -35,6 +35,10 @@ For very vast requests cases, use a combination of streaming and go net.
 
 If the framework reports the following error codes, you can check it for possible causes. If there is an error code other than the following, the error code is not caused by the framework and needs to be located by the user to see whether it is set by itself or by some middleware.
 
+### 403
+
+This status code is returned only when the `fs` feature is enabled and a directory index is accessed without permission. Hertz does not return `403` in other scenarios.
+
 ### 404
 
 1. Access to the wrong port, commonly access to the debug port.
@@ -43,10 +47,18 @@ If the framework reports the following error codes, you can check it for possibl
    1. Check whether all expected routes are registered correctly based on the startup log.
    2. Check that the access method is correct.
 
+### 413
+
+The request body sent by the client exceeds the maximum size configured by [`WithMaxRequestBodySize`](../reference/config.md) on the server side. The default limit is 4 MB.
+
 ### 417
 
 The server returns `false` after executing the custom `ContinueHandler` (the server actively rejects the subsequent body of the 100 Continue).
 
+### 431
+
+The request header sent by the client exceeds the maximum size configured by [`WithMaxHeaderBytes`](../reference/config.md) on the server side. The default limit is 1 MB.
+
 ### 500
 
 1. Throwing the panic in middleware or in `handlerFunc`.

content/zh/docs/hertz/faq/_index.md

@@ -29,6 +29,10 @@ description: "Hertz 常见问题解答。"
 
 如果框架报以下的错误码，可以按照可能原因进行排查。如果出现非以下错误码，则不是框架打出来的，需要由使用方定位一下是否自行设置或者由某些中间件设置了错误码。
 
+### 403
+
+仅在启用fs功能，访问无权限的目录索引时才会出现403错误码，其他场景下不会出现403错误码。
+
 ### 404
 
 1. 访问到了错误的端口上了，常见访问到了 debug 端口
@@ -37,10 +41,18 @@ description: "Hertz 常见问题解答。"
    1. 根据启动日志查看是否所有预期路由都正常注册
    2. 查看访问方法是否正确
 
+### 413
+
+client 发送的请求体（request body）大小超出服务端配置 [`WithMaxRequestBodySize`](../reference/config.md) 的最大值（默认为 4MB）。
+
 ### 417
 
 server 在执行完自定义的 `ContinueHandler` 之后返回 `false`（server 主动拒绝掉 100 Continue 后续的 body）。
 
+### 431
+
+client 发送的请求头（request header）大小超出服务端配置 [`WithMaxHeaderBytes`](../reference/config.md) 的最大值（默认为 1MB）。
+
 ### 500
 
 1. 中间件或者 `handlerFunc` 中抛 panic