doc: update build guide of macOS

Author: Bambooin

README.md

@@ -91,19 +91,19 @@ make release
 
 #### macOS
 
-1. It's recommended that install Android [SDK](https://developer.android.com/studio/index.html) and [NDK](https://developer.android.com/ndk/index.html) manually or via Android Studio.
-2. Install [Homebrew](http://brew.sh/) (If your is network is too slow, you could setup a [Homebrew mirror](https://mirrors.ustc.edu.cn/help/brew.git.html)), then run:
+1. Install [Android SDK](https://developer.android.com/sdk/index.html)
 
+2. Set up ANDROID_SDK_ROOT
   ```bash
-   brew install automake cmake opencc boost python gradle doxygen clang capnp
+  # Android
+   export ANDROID_SDK_ROOT="android_sdk_path"
   ```
 
-  Set the following environment variables in your `~/.bashrc` is recommended：
+3. Set up [mirror](https://mirrors.tuna.tsinghua.edu.cn/help/homebrew/) of Homebrew(Optional)
+
+4. Install [Homebrew](https://brew.sh/)
   ```bash
-   # Android
-   export ANDROID_HOME="your_android_sdk"
-   export ANDROID_NDK="your_android_ndk"
-   export PATH=${PATH}:$ANDROID_HOME/tools:$ANDROID_HOME/platform-tools:$ANDROID_NDK
+   brew install cmake capnp
   ```
 
 ## Third Party Libraries

README_sc.md

@@ -83,20 +83,21 @@ make release
 
 #### macOS
 
-1. 推荐通过 Android Studio 或手动安装 Android [SDK](https://developer.android.com/studio/index.html) 和 [NDK](https://developer.android.com/ndk/index.html)。
-2. 安装 [Homebrew](http://brew.sh/)（如果网速过慢，可设置 [Homebrew 镜像](https://mirrors.ustc.edu.cn/help/brew.git.html)），然后运行：
+1. 安装 [Android SDK](https://developer.android.com/sdk/index.html)
 
+2. 设置相应的 ANDROID_SDK_ROOT
   ```bash
-   brew install automake cmake opencc boost python gradle doxygen clang capnp
+  # Android
+   export ANDROID_SDK_ROOT="android_sdk_path"
   ```
 
-  如果使用 bash，请在 ~/.bashrc 中设置环境变量：
+3. 设置 Homebrew [镜像](https://mirrors.tuna.tsinghua.edu.cn/help/homebrew/)(可选)
+
+4. 安装 [Homebrew](https://brew.sh/)
   ```bash
-   # Android
-   export ANDROID_HOME="your_android_sdk"
-   export ANDROID_NDK="your_android_ndk"
-   export PATH=${PATH}:$ANDROID_HOME/tools:$ANDROID_HOME/platform-tools:$ANDROID_NDK
+   brew install cmake capnp
   ```
+
 ## 第三方库
 - [Boost C++ Libraries](https://www.boost.org/) (Boost Software License)
 - [Cap'n Proto](https://capnproto.org/) (MIT License)

README_tc.md

@@ -82,20 +82,21 @@ make release
 
 #### macOS
 
-1. 推薦通過 Android Studio 或手動安裝 Android [SDK](https://developer.android.com/studio/index.html) 和 [NDK](https://developer.android.com/ndk/index.html)。
-2. 安裝 [Homebrew](http://brew.sh/)（如果網速過慢，可設置 [Homebrew 鏡像](https://mirrors.ustc.edu.cn/help/brew.git.html)），然後執行：
+1. 安裝 [Android SDK](https://developer.android.com/sdk/index.html)
 
+2. 設置相應的 ANDROID_SDK_ROOT
   ```bash
-   brew install automake cmake opencc boost python gradle doxygen clang capnp
+  # Android
+   export ANDROID_SDK_ROOT="android_sdk_path"
   ```
 
-  如果使用 bash，請在 ~/.bashrc 中設置環境變數：
+3. 設置 Homebrew [鏡像](https://mirrors.tuna.tsinghua.edu.cn/help/homebrew/)(可選)
+
+4. 安裝 [Homebrew](https://brew.sh/)
   ```bash
-   # Android
-   export ANDROID_HOME="your_android_sdk"
-   export ANDROID_NDK="your_android_ndk"
-   export PATH=${PATH}:$ANDROID_HOME/tools:$ANDROID_HOME/platform-tools:$ANDROID_NDK
+   brew install cmake capnp
   ```
+
 ## 第三方庫
 - [Boost C++ Libraries](https://www.boost.org/) (Boost Software License)
 - [Cap'n Proto](https://capnproto.org/) (MIT License)