HtmlWebSocketChannel docs are outdated

The [HtmlWebSocketChannel](https://pub.dev/documentation/web_socket_channel/latest/html/HtmlWebSocketChannel-class.html) docs and its [constructor](https://pub.dev/documentation/web_socket_channel/latest/html/HtmlWebSocketChannel/HtmlWebSocketChannel.html) docs both say this uses dart:html, which it does not (it uses package:web).