update adb in mac code example

Example 1: install adb on mac

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"
 brew cask install android-platform-tools
 adb devices

Example 2: install adb on mac

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"