fix on_device_inference

tutorials/source_en/advanced_use/on_device_inference.md

@@ -48,8 +48,6 @@ The environment requirements are as follows:
   - [GCC](https://gcc.gnu.org/releases.html) >= 5.4
   - [Android_NDK r20b](https://dl.google.com/android/repository/android-ndk-r20b-linux-x86_64.zip)
                                                                                                                                                                                                                
-  > The stallation of `Android_NDK` is needed only when using arm. This time we choose to use x86, so you can skip this step. 
-                                                                                                                                                                                                                   
   Using MindSpore Lite converter tool needs to add more dependencies：
   - [autoconf](http://ftp.gnu.org/gnu/autoconf/) >= 2.69
   - [libtool](https://www.gnu.org/software/libtool/) >= 2.4.6
@@ -69,10 +67,29 @@ The compilation procedure is as follows:
 
 2. Run the following command in the root directory of the source code to compile MindSpore Lite.
 
+   - Compile converter tool:
+   
        ```bash
        bash build.sh -I x86_64
        ```
    
+   - Compile inference platform:
+   
+       Set path of ANDROID_NDK:
+       ```bash
+       export ANDROID_NDK={$NDK_PATH}/android-ndk-r20b 
+       ```
+   
+       According to the phone，you can choose`arm64`:
+       ```bash
+       bash build.sh -I arm64
+       ```   
+   
+       or`arm32`:
+       ```bash
+       bash build.sh -I arm32
+       ```
+
 3. Go to the `mindspore/output` directory of the source code to obtain the compilation result. Unzip `MSLite-0.6.0-linux_x86_64.tar.gz` to get the result after building. 
       
    ```bash

tutorials/source_zh_cn/advanced_use/on_device_inference.md

@@ -48,8 +48,6 @@ MindSpore Lite的框架主要由Frontend、IR、Backend、Lite RT、Micro构成
   - [GCC](https://gcc.gnu.org/releases.html) >= 5.4
   - [Android_NDK r20b](https://dl.google.com/android/repository/android-ndk-r20b-linux-x86_64.zip)
                                                                                                                                                                                                                    
-  > 仅在使用arm架构时需要安装`Android_NDK`，本示例采用x86，可跳过此项。
-                                                                                                                                                                                                                   
   使用MindSpore Lite转换工具，需要添加更多的依赖项：
   - [autoconf](http://ftp.gnu.org/gnu/autoconf/) >= 2.69
   - [libtool](https://www.gnu.org/software/libtool/) >= 2.4.6
@@ -68,10 +66,29 @@ MindSpore Lite的框架主要由Frontend、IR、Backend、Lite RT、Micro构成
 
 2. 在源码根目录下，执行如下命令编译MindSpore Lite。
    
+   - 编译转换工具： 
+   
        ```bash
        bash build.sh -I x86_64
        ```
    
+   - 编译推理框架：
+   
+       设定ANDROID_NDK路径：
+       ```bash
+       export ANDROID_NDK={$NDK_PATH}/android-ndk-r20b 
+       ```
+   
+       用户需根据设备情况，可选择`arm64`：
+       ```bash
+       bash build.sh -I arm64
+       ```   
+   
+       或`arm32`：
+       ```bash
+       bash build.sh -I arm32
+       ```
+
 3. 进入源码的`mindspore/output`目录，获取编译结果`MSLite-0.6.0-linux_x86_64.tar.gz`。执行解压缩命令，获得编译后的工具包：
    
    ```bash