updated: navigation_drawer example with better implementation
updated: navigation_drawer example with better implementation

nisrulz/flutter-examples,nisrulz/flutter-examples,nisrulz/flutter-examples,nisrulz/flutter-examples,nisrulz/flutter-examples,nisrulz/flutter-examples,nisrulz/flutter-examples,nisrulz/flutter-examples,nisrulz/flutter-examples