[PAGE ISSUE]: Update URL strategy page

[johnpryan]

Page URL

https://docs.flutter.dev/development/ui/navigation/url-strategies/

Page source

https://github.com/flutter/website/tree/main/src/development/ui/navigation/url-strategies.md

Describe the problem

This page should update it's instructions now that flutter_web_plugins allows the usage of url strategies without conditional imports

import 'package:flutter_web_plugins/url_strategy.dart';

void main() {
  usePathUrlStrategy();
  runApp(ExampleApp());
}