Update install.md (#1127)

test=doc_fix

docs/source/install.md

 # Installation
 There are 3 ways to use `PaddleSpeech`. According to the degree of difficulty, the 3 ways can be divided into **Easy**, **Medium** and **Hard**. You can choose one of the 3 ways to install `PaddleSpeech`.
 
-| Way | Function                                                     |
-| :---- | :----------------------------------------------------------- |
-| Easy     | (1) Use command line functions of PaddleSpeech. <br> (2) Experience PaddleSpeech on Aistudio. |
-| Medium     | Support major function，such as using the` ready-made `examples and using PaddleSpeech to train your own model.                                           |
-| Hard     | Support full function of Paddlespeech，including training n-gram language model. And you are more able be a developer! |
+| Way | Function                                                     | Support|
+| :---- | :----------------------------------------------------------- |:----|
+| Easy     | (1) Use command line functions of PaddleSpeech. <br> (2) Experience PaddleSpeech on Ai Studio. | Linux, Mac，Windows |
+| Medium     | Support major function，such as using the` ready-made `examples and using PaddleSpeech to train your own model.                                           | Linux |
+| Hard     | Support full function of Paddlespeech，including training n-gram language model, montreal-forced-aligner and so on. And you are more able be a developer! | Ubuntu |
 
 
 ## Prerequisites
 - Python >= 3.7
-- PaddlePaddle latest version (please refer to the [Installation Guide](https://www.paddlepaddle.org.cn/documentation/docs/en/beginners_guide/index_en.html))
-- Hip: For Linux and Mac, do not use command `sh` instead of command `bash`
+- PaddlePaddle latest version (please refer to the [Installation Guide] (https://www.paddlepaddle.org.cn/documentation/docs/en/beginners_guide/index_en.html))
+- C++ compilation environment
+- Hip: For Linux and Mac, do not use command `sh` instead of command `bash` in installation document.
 
 ## Easy: Get the Basic Function (Support Linux, Mac and Windows)
 - If you are newer to `PaddleSpeech` and want to experience it easily without your own machine. We recommend you to use [AI Studio](https://aistudio.baidu.com/aistudio/index) to experience it. There is a step-by-step tutorial for `PaddleSpeech` and you can use the basic function of `PaddleSpeech` with a free machine. 
+- If you want to use the command line function of Paddlespeech, you need to complete the following steps to install `PaddleSpeech`. For more information about how to use command line function , you can see the [cli](https://github.com/PaddlePaddle/PaddleSpeech/tree/develop/paddlespeech/cli).
 ### Install Conda
-Conda is a management system of the environment. You can go to [minicoda](https://docs.conda.io/en/latest/miniconda.html) to install the conda.
+Conda is a management system of the environment. You can go to [minicoda](https://docs.conda.io/en/latest/miniconda.html)  (select a version py>=3.7) to download and install the conda.
 And then Install  conda dependencies for `paddlespeech` :
 
 ```bash
-conda install -y -c conda-forge sox libsndfile swig bzip2
+conda install -y -c conda-forge sox libsndfile bzip2
 ```
-### Install C++ environment
+### Install C++ Compilation Environment 
+
+(If you already have C++ compilation environment, you can miss this step.)
 
 #### Windows
-Since some required pypi packages need C++ environment, you need to install the visual studio firstly.
+You need to install the `Visual Studio` to make the C++ compilation environment.
 
 #### Mac
 ```bash
@@ -51,11 +55,9 @@ You can use the following command:
 pip install paddlepaddle paddlespeech
 ```
 
-- You can use the command line function of Paddlespeech. For more information, you can see the [cli](https://github.com/PaddlePaddle/PaddleSpeech/tree/develop/paddlespeech/cli).
-
 
 ## Medium: Get the Major Function (Support Linux)
-If you want to get the major function of  `paddlespeech`. There are 3 steps you need to do.
+If you want to get the major function of  `paddlespeech`. There are 4 steps you need to do.
 
 ### Install Conda
 Conda is a management system of the environment. You can go to [minicoda](https://docs.conda.io/en/latest/miniconda.html) to select a version (py>=3.7) and install it by yourself or you can use the following command:
@@ -81,8 +83,10 @@ Install  conda dependencies for `paddlespeech` :
 ```bash
 conda install -y -c conda-forge sox libsndfile swig bzip2
 ```
+### Install C++ Compilation Environment 
+(If you already have C++ compilation environment, you can miss this step.)
 Do not forget to install `gcc` and `gxx` on your system.
-If you use linux, you can choose to use the scripts below to install them.
+You can choose to use the scripts below to install them.
 
 ```bash
 #  centos
@@ -98,23 +102,24 @@ conda install -y -c gcc_linux-64=8.4.0 gxx_linux-64=8.4.0
 ```
 (Hip: Do not use the last script if you want to install by **Hard** way):
 ### Install PaddlePaddle
-For example, for CUDA 10.2, CuDNN7.5 install paddle 2.2.0:
+You can choose the `PaddlePaddle` version based on your system. For example, for CUDA 10.2, CuDNN7.5 install paddlepaddle-gpu 2.2.0:
 ```bash
 python3 -m pip install paddlepaddle-gpu==2.2.0
 ```
 ### Install PaddleSpeech 
-If you want to use the` ready-made `examples in `paddlespeech`, you need to clone this repository and install  `paddlespeech`  by the following commands:
+You need to `git clone` this repository and install  `paddlespeech`  by the following commands，then you can use the `ready-made` examples in `paddlespeech` :
 ```bash
 https://github.com/PaddlePaddle/PaddleSpeech.git
 cd PaddleSpeech
 pip install .
 ```
-## Hard: Get the Full Function on Your Machine
+## Hard: Get the Full Function (Support Ubuntu)
 ### Prerequisites
+- Ubuntu >= 16.04.
 - choice 1: working with `Ubuntu` Docker Container.
 - choice 2: working on `Ubuntu` with `root` privilege. 
 
-To avoid the trouble of environment setup, [running in Docker container](#running-in-docker-container) is highly recommended. Otherwise, if you work on `Ubuntu` with `root` privilege, you can skip the next step.
+To avoid the trouble of environment setup, running in Docker container is highly recommended. Otherwise, if you work on `Ubuntu` with `root` privilege, you can still complete the installation.
 
 ### Choice 1: Running in Docker Container (Recommand)
 Docker is an open-source tool to build, ship, and run distributed applications in an isolated environment. A Docker image for this project has been provided in [hub.docker.com](https://hub.docker.com) with all the dependencies installed. This Docker image requires the support of NVIDIA GPU, so please make sure its availability and the [nvidia-docker](https://github.com/NVIDIA/nvidia-docker) has been installed.
@@ -135,7 +140,12 @@ git clone https://github.com/PaddlePaddle/PaddleSpeech.git
 ```bash
 sudo nvidia-docker run --net=host --ipc=host --rm -it -v $(pwd)/PaddleSpeech:/PaddleSpeech registry.baidubce.com/paddlepaddle/paddle:2.2.0-gpu-cuda10.2-cudnn7 /bin/bash
 ```
+- Enter PaddleSpeech directory.
+```bash
+cd /PaddleSpeech
+```
 Now you can execute training, inference and hyper-parameters tuning in  Docker container.
+
 ### Choice 2: Running in Ubuntu with Root Privilege
 - Install `build-essential` by apt
 ```bash
@@ -144,10 +154,8 @@ sudo apt install build-essential
 - Clone this repository
 ```bash
 git clone https://github.com/PaddlePaddle/PaddleSpeech.git
-```
-- Install paddle 2.2.0:
-```bash
-python3 -m pip install paddlepaddle-gpu==2.2.0
+# Enter the PaddleSpeech dir
+cd PaddleSpeech
 ```
 ### Install the Conda
 ```bash
@@ -165,12 +173,12 @@ conda activate tools/venv
 conda install -y -c conda-forge sox libsndfile swig bzip2 libflac bc
 ```
 ### Install PaddlePaddle
-For example, for CUDA 10.2, CuDNN7.5 install paddle 2.2.0:
+Make sure you have GPU and the paddlepaddle version is right. For example, for CUDA 10.2, CuDNN7.5 install paddle 2.2.0:
 
 ```bash
 python3 -m pip install paddlepaddle-gpu==2.2.0
 ```
-### Get the Function for Developing PaddleSpeech
+### Install PaddleSpeech in Developing Mode
 ```bash
 pip install -e .[develop]
 ```
@@ -182,8 +190,3 @@ bash extras/install_kaldi.sh
 popd
 ```
 
-
-## Setup for Other Platform 
-- Make sure these libraries or tools in [dependencies](./dependencies.md) installed. More information please see: `setup.py `and `tools/Makefile`.
-- The version of `swig` should >= 3.0
-- we will simplify the install process in the future.