docs(kitex): clarify io.EOF meaning in streaming documentation

Author: XinyiWang0204

content/en/docs/kitex/Tutorials/advanced-feature/generic-call/generic_streaming.md

@@ -154,7 +154,7 @@ strResp, ok := resp.(string) // response is json string
 
 ### Server Streaming
 
-Note: A non-nil error (including `io.EOF`) returned by `Recv` indicates that the server has finished sending (or encountered an error)
+Note: An `io.EOF` error returned by `Recv` indicates that the server has finished sending and normally closed the stream, while other non-nil errors indicate actual errors.
 
 Example:
 

content/zh/docs/kitex/Tutorials/advanced-feature/generic-call/generic_streaming.md

@@ -1,6 +1,6 @@
 ---
 title: "流式泛化调用用户指南"
-date: 2025-05-09
+date: 2025-05-12
 weight: 6
 keywords: ["流式泛化调用用户指南"]
 description: ""
@@ -159,7 +159,7 @@ strResp, ok := resp.(string) // 响应为 json 字符串
 
 ### 服务端流（Server Streaming）
 
-注意：`Recv` 返回非 nil 错误（包括 `io.EOF`）表示服务端已发送完毕或出错。
+注意：`Recv` 返回 `io.EOF` 错误表示服务端已发送完毕并正常关闭流，其它非 nil 错误表示出错。
 
 示例：