fix: callback after register user remove secret (#211)

Author: icey-yu

docs/restapi/webhooks/user/userRegisterAfter.mdx

@@ -37,7 +37,6 @@ App 业务服务端可以通过该回调获取用户注册的请求，App 后台
 ```json
 {
   "callbackCommand": "callbackAfterUserRegisterCommand",
-  "secret": "YourSecretKey",
   "users": {
     "userID": "user123",
     "nickname": "John Doe",
@@ -55,7 +54,6 @@ App 业务服务端可以通过该回调获取用户注册的请求，App 后台
 | 字段             | 类型   | 描述                                 |
 | ---------------- | ------ | ------------------------------------ |
 | callbackCommand  | string | 回调命令，这里是用户用户注册后的回调 |
-| secret           | string | 用于验证的密钥                       |
 | users            | object | 用户信息对象                         |
 | userID           | string | 用户的唯一标识符                     |
 | nickname         | string | 用户的昵称                           |

i18n/en/docusaurus-plugin-content-docs-restapi/current/webhooks/user/userRegisterAfter.mdx

@@ -41,7 +41,6 @@ https://callbackurl?command=$UserRegisterCommand&contenttype=json
 ```json
 {
   "callbackCommand": "userRegisterAfterCommand",
-  "secret": "YourSecretKey",
   "users": {
     "userID": "user123",
     "nickname": "John Doe",
@@ -59,7 +58,6 @@ https://callbackurl?command=$UserRegisterCommand&contenttype=json
 | Field              | Type    | Description                       |
 |--------------------|---------|-----------------------------------|
 | callbackCommand    | string  | Callback command, here for post-user registration callback. |
-| secret             | string  | Secret key for verification.      |
 | users              | object  | User information object.          |
 | userID             | string  | Unique identifier of the user.    |
 | nickname           | string  | Nickname of the user.             |