Update environments_en.md

doc/doc_en/environment_en.md

@@ -2,12 +2,19 @@
 
 Windows and Mac users are recommended to use Anaconda to build a Python environment, and Linux users are recommended to use docker to build a Python environment. If you are familiar with the Python environment, you can skip to step 2 to install PaddlePaddle.
 
+Recommended working environment:
+- PaddlePaddle >= 2.0.0 (2.1.2)
+- python3.7
+- CUDA10.1 / CUDA10.2
+- CUDNN 7.6
+
 * [1. Python Environment Setup](#1)
   + [1.1 Windows](#1.1)
   + [1.2 Mac](#1.2)
   + [1.3 Linux](#1.3)
 * [2. Install PaddlePaddle 2.0](#2)
 
+
 <a name="1"></a>
 
 ## 1. Python Environment Setup
@@ -204,7 +211,6 @@ Linux users can choose to run either Anaconda or Docker. If you are familiar wit
   <img src="../install/linux/anaconda_download.png" akt="anaconda download" width="800" align="center"/>
 
 
-
   - Select the appropriate version for your operating system
       - Type `uname -m` in the terminal to check the command set used by your system
 
@@ -316,6 +322,13 @@ sudo docker run --name ppocr -v $PWD:/paddle --network=host -it registry.baidubc
 # If using GPU, use nvidia-docker to create docker
 # docker image registry.baidubce.com/paddlepaddle/paddle:2.1.3-gpu-cuda11.2-cudnn8 is recommended for CUDA11.2 + CUDNN8.
 sudo nvidia-docker run --name ppocr -v $PWD:/paddle --shm-size=64G --network=host -it registry.baidubce.com/paddlepaddle/paddle:2.1.3-gpu-cuda10.2-cudnn7 /bin/bash
+
+```
+You can also visit [DockerHub](https://hub.docker.com/r/paddlepaddle/paddle/tags/) to get the image that fits your machine.
+
+```
+# ctrl+P+Q to exit docker, to re-enter docker using the following command:
+sudo docker container exec -it ppocr /bin/bash
 ```
 
 <a name="2"></a>
@@ -335,4 +348,3 @@ python3 -m pip install paddlepaddle -i https://mirror.baidu.com/pypi/simple
 ```
 
 For more software version requirements, please refer to the instructions in [Installation Document](https://www.paddlepaddle.org.cn/install/quick) for operation.
-