update dart sdk android studio code example

Example 1: dart update

C:\> choco upgrade dart-sdk

Example 2: set dart sdk from android studio

1- File>> Settings (ctrl+alt+s) >>Languages and Frameworks -> Dart
2- Check "Enable Dart support for the project..."
In "Dart SDK path" click in "..." and navigate to flutter SDK directory 
.../flutter/bin/cache/dart-sdk/bin
3- Apply >>ok

Example 3: dart update

C:\> choco install dart-sdk