New and updated docs on the site include:

We’ve revamped the Showcase page.

The Flutter layout codelab has been rewritten and
uses the updated DartPad, the browser-based tool for
running Dart code. DartPad now supports Flutter!
Try it out and let us know what you think.

A new page on using the dart:ffi library
to bind your app to native code (a feature currently under
development).

The Performance view tool, which allows you to record
and profile a session from your Dart/Flutter application,
has been enabled in DevTools. For more information,
see the Performance view page.

A new page on
building a web application.

A new page on creating responsive apps in Flutter.

A new page on preparing a web app for release.

A new web FAQ.

The Flutter for web page is updated.

Other relevant docs: