[workflow] polish readme and dockerfile (#1165)

* [workflow] polish readme and dockerfile

* polish

README-zh-Hans.md

@@ -196,6 +196,12 @@ NO_CUDA_EXT=1 pip install .
 
 ## 使用 Docker
 
+### 从DockerHub获取镜像
+
+您可以直接从我们的[DockerHub主页](https://hub.docker.com/r/hpcaitech/colossalai)获取最新的镜像，每一次发布我们都会自动上传最新的镜像。
+
+### 本地构建镜像
+
 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)。

README.md

@@ -201,11 +201,19 @@ NO_CUDA_EXT=1 pip install .
 
 ## Use Docker
 
+### Pull from DockerHub
+
+You can directly pull the docker image from our [DockerHub page](https://hub.docker.com/r/hpcaitech/colossalai). The image is automatically uploaded upon release.
+
+
+### Build On Your Own
+
 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

docker/Dockerfile

@@ -12,3 +12,6 @@ RUN git clone https://github.com/NVIDIA/apex && \
 RUN git clone https://github.com/hpcaitech/ColossalAI.git \
  && cd ./ColossalAI \
  && pip install -v --no-cache-dir .
+
+# install titans
+RUN pip install -no-cache-dir titans