[typo](docs)Add upgrade precautions #17027

docs/en/docs/admin-manual/cluster-management/upgrade.md

@@ -78,6 +78,9 @@ Doris can upgrade smoothly by rolling upgrades. The following steps are recommen
 9. If the startup is successful, run sh bin/stop_fe.sh to stop the FE process of the test environment.
 10. **The purpose of the above 2-6 steps is to prevent the FE of the test environment from being misconnected to the online environment after it starts.**
 
+**Note:**
+1.1.x Before upgrading 1.2.x, you need to delete existing Native UDF ; otherwise, FE startup fails ; And since version 1.2 no longer supports Native UDF, please use [Java UDF](../../ecosystem/udf/java-user-defined-function.md).
+
 ## Upgrade preparation
 
 1. After data validation, the new version of BE and FE binary files are distributed to their respective directories.

docs/zh-CN/docs/admin-manual/cluster-management/upgrade.md

@@ -83,6 +83,9 @@ Doris 可以通过滚动升级的方式，平滑进行升级。建议按照以
 9. 如果启动成功，运行 sh bin/stop_fe.sh 停止测试环境的 FE 进程。
 10. **以上 2-6 步的目的是防止测试环境的FE启动后，错误连接到线上环境中。**
 
+**注：**
+1.1.x 版本升级 1.2.x 版本时，需要先删除已有的原生 UDF ；否则会导致FE启动失败；并且1.2版本开始不再对原生 UDF提供支持，请使用 [Java UDF](../../ecosystem/udf/java-user-defined-function.md)。
+
 ## 升级准备
 
 1. 在完成数据正确性验证后，将 BE 和 FE 新版本的二进制文件分发到各自目录下。