[doc] update docker instruction (#1020)

README-zh-Hans.md

@@ -178,6 +178,9 @@ NO_CUDA_EXT=1 pip install .
 
 运行以下命令从我们提供的 docker 文件中建立 docker 镜像。
 
+> 在Dockerfile里编译Colossal-AI需要有GPU支持，您需要将Nvidia Docker Runtime设置为默认的Runtime。更多信息可以点击[这里](https://stackoverflow.com/questions/59691207/docker-build-with-nvidia-runtime)。
+> 我们推荐从[项目主页](https://www.colossalai.org)直接下载Colossal-AI.
+
 ```bash
 cd ColossalAI
 docker build -t colossalai ./docker

README.md

@@ -183,6 +183,9 @@ NO_CUDA_EXT=1 pip install .
 
 Run the following command to build a docker image from Dockerfile provided.
 
+> Building Colossal-AI from scratch requires GPU support, you need to use Nvidia Docker Runtime as the default when doing `docker build`. More details can be found [here](https://stackoverflow.com/questions/59691207/docker-build-with-nvidia-runtime).
+> We recommend you install Colossal-AI from our [project page](https://www.colossalai.org) directly.
+
 ```bash
 cd ColossalAI
 docker build -t colossalai ./docker