[Docs]: Update doc for openvino installation (#102)

* fix docs

* fix docs

* fix docs

* fix mmcv version

* fix docs

* rm blank line

Author: VVsssssk

docs/en/backends/openvino.md

@@ -1,23 +1,16 @@
 ## OpenVINO Support
 
 This tutorial is based on Linux systems like Ubuntu-18.04.
-
 ### Installation
 It is recommended to create a virtual environment for the project.
 1. Install [OpenVINO](https://docs.openvino.ai/2021.4/get_started.html). It is recommended to use the installer or install using pip.
 Installation example using [pip](https://pypi.org/project/openvino-dev/):
 ```bash
 pip install openvino-dev
 ```
-2. Install [PyTorch](https://pytorch.org/get-started/locally/).
-```bash
-pip install torch torchvision
-```
-3. Install [MMCV](https://mmcv.readthedocs.io/en/latest/get_started/installation.html). It is advisable to install the latest version `mmcv-full`.
-```bash
-pip install mmcv-full
-```
-4. Install MMDeploy following the [instructions](../build.md).
+2. *`Optional` If you want to use OpenVINO in SDK, you need install OpenVINO with [install_guides](https://docs.openvino.ai/2021.4/openvino_docs_install_guides_installing_openvino_linux.html#install-openvino).
+
+3. Install MMDeploy following the [instructions](../build.md).
 
 To work with models from [MMDetection](https://github.com/open-mmlab/mmdetection/blob/master/docs/get_started.md), you may need to install it additionally.
 

docs/en/build.md

@@ -75,9 +75,11 @@ We provide building methods for both physical and virtual machines. For virtual
     ```bash
     export cu_version=cu111 # cuda 11.1
     export torch_version=torch1.8.0
-    pip install mmcv-full -f https://download.openmmlab.com/mmcv/dist/${cu_version}/${torch_version}/index.html
+    pip install mmcv-full==1.4.0 -f https://download.openmmlab.com/mmcv/dist/${cu_version}/${torch_version}/index.html
     ```
 
+
+
 ### Build backend support
 
 Build the inference engine extension libraries you need.

docs/en/get_started.md

@@ -104,7 +104,7 @@ conda activate openmmlab
 conda install pytorch==1.8.0 torchvision==0.9.0 cudatoolkit=10.2 -c pytorch -y
 
 # install the latest mmcv
-pip install mmcv-full -f https://download.openmmlab.com/mmcv/dist/cu102/torch1.8.0/index.html
+pip install mmcv-full==1.4.0 -f https://download.openmmlab.com/mmcv/dist/cu102/torch1.8.0/index.html
 
 # install mmdetection
 git clone https://github.com/open-mmlab/mmdetection.git

docs/zh_cn/build.md

@@ -75,7 +75,7 @@
     ```bash
     export cu_version=cu111 # cuda 11.1
     export torch_version=torch1.8.0
-    pip install mmcv-full -f https://download.openmmlab.com/mmcv/dist/${cu_version}/${torch_version}/index.html
+    pip install mmcv-full==1.4.0 -f https://download.openmmlab.com/mmcv/dist/${cu_version}/${torch_version}/index.html
     ```
 
 ### 安装推理引擎

docs/zh_cn/get_started.md

@@ -104,7 +104,7 @@ conda activate openmmlab
 conda install pytorch==1.8.0 torchvision==0.9.0 cudatoolkit=10.2 -c pytorch -y
 
 # 安装最新的mmcv
-pip install mmcv-full -f https://download.openmmlab.com/mmcv/dist/cu102/torch1.8.0/index.html
+pip install mmcv-full==1.4.0 -f https://download.openmmlab.com/mmcv/dist/cu102/torch1.8.0/index.html
 
 # 安装mmdetection
 git clone https://github.com/open-mmlab/mmdetection.git