Lift docs from Markdown to dartdoc

I've also removed the top-level description of the Sky package. Instead, we
should host that content on flutter.io.

packages/flutter/README.md

-Sky
-===
+Flutter
+=======
 
-Sky is a new way to build high-performance, cross-platform mobile apps.
-Sky is optimized for today's, and tomorrow's, mobile devices. We are
+Flutter is a new way to build high-performance, cross-platform mobile apps.
+Flutter is optimized for today's, and tomorrow's, mobile devices. We are
 focused on low-latency input and high frame rates on Android and iOS.
 
 See the [getting started guide](https://flutter.github.io/getting-started/) for

packages/flutter/lib/README.md

-SKY SDK
-========
-
-Sky and Sky's SDK are designed as layered frameworks, where each layer
-depends on the ones below it but could be replaced wholesale.
-
-The bottom-most layer is the Sky Platform, which is exposed to Dart
-code as [various `dart:` packages](https://api.dartlang.org/),
-including `dart:sky`.
-
-Above this layer is the [animation](animation.dart) library,
-which provides core animation primitives, and the [gestures/](gestures/)
-directory, which define a gesture recognition and disambiguation system.
-
-The next layer consists of the [painting](painting.dart) library,
-which provides APIs related to drawing graphics. Some of the code here
-uses the [animation](animation.dart) library mentioned above.
-
-Layout primitives are provided in the next layer, found in the
-[rendering](rendering.dart) library. They use `dart:sky` and the
-APIs exposed in the [painting](painting.dart) library to provide a retained-mode
-layout and rendering model for applications or documents.
-
-Widgets are provided by the files in the [widgets](widgets.dart)
-library, using a reactive framework. They use data given in the
-[theme/](theme/) directory to select styles consistent with Material
-Design.
-
-Alongside the above is the [mojo/](mojo/) directory, which contains
-anything that uses the Mojo IPC mechanism, typically as part of
-wrapping host operating system features. Some of those Host APIs are
-implemented in the host system's preferred language.
-
-Here is a diagram summarizing all this:
-
-    +-----------------------------+ ------
-    |           YOUR APP          |
-    |  +----------------------+---+
-    |  |  widgets   (theme/)  |   |
-    | ++---------------------++   |
-    | |      rendering       |    |  Dart
-    | |---------+------------+    |
-    | |         | painting   |    |
-    +-+         +------------+    |
-    | gestures/ | animation  |    |
-    +-----------+------------+    |
-    |             mojo/           |
-    +------------+--+-+----+------+ -------
-    |  dart:sky  |    |    | Host |
-    +--------+---+    |    | APIs |  C++
-    |  Skia  |  Dart  |    +------+  ObjC
-    +--------+--------+           |  Java
-    |            Mojo             |
-    +-----------------------------+ -------
-    |    Host Operating System    |  C/C++
-    +-----------------------------+ -------
-
-TODO(ianh): document dart:sky and the Host APIs somewhere
-
-Sky Engine API
---------------
-
-The Sky engine API provides efficient, immutable wrappers
-for common Skia C++ types, notably Color, Point, and Rect.
-Because these wrappers are immutable, they are suitable
-for storage in final member variables of widget classes.
-More complex Skia wrappers such as Paint and RRect are
-mutable, to more closely match the Skia APIs. We recommend
-constructing wrappers for complex Skia classes dynamically
-during the painting phase based on the underlying state of
-the widget.

packages/flutter/lib/animation.dart

@@ -2,9 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-/// The Sky animation engine.
+/// The Flutter animation engine.
 ///
-/// This library includes and re-exports all Sky animation classes.
+/// This library depends only on core Dart libraries and the `newton` package.
 library animation;
 
 export 'src/animation/animated_simulation.dart';

packages/flutter/lib/gestures.dart

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-/// The Sky gesture recognizers
+/// The Flutter gesture recognizers
 library gestures;
 
 export 'src/gestures/arena.dart';

packages/flutter/lib/material.dart

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-/// Widgets implementing Material Design
+/// Flutter widgets implementing Material Design
 ///
 /// See https://www.google.com/design/spec/material-design/introduction.html
 library material;

packages/flutter/lib/painting.dart

@@ -2,11 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-/// Utilities for painting.
+/// The Flutter painting library
 ///
-/// This library includes and re-exports a variety of classes that wrap the Sky
+/// This library includes a variety of classes that wrap the Sky
 /// engine's painting API for more specialised purposes, such as painting scaled
 /// images, interpolating between shadows, painting borders around boxes, etc.
+///
+/// This library depends only on the core Dart libraries and animation.dart.
+/// Note: animation.dart depends on the `newton` package.
 library painting;
 
 export 'src/painting/box_painter.dart';

packages/flutter/lib/rendering.dart

@@ -2,9 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-/// The Sky render tree.
-///
-/// This library includes and re-exports all Sky rendering classes.
+/// The Flutter rendering tree
 library rendering;
 
 export 'package:sky/src/rendering/auto_layout.dart';

packages/flutter/lib/services.dart

@@ -2,7 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-/// Services provided by Mojo
+/// System services exposed to Flutter apps
+///
+/// For example, this library includes [fetch], which fetches data from the
+/// network.
+///
+/// This library depends only on core Dart libraries as well as the `mojo`,
+/// `mojo_services`, and `sky_services` and packages.
 library services;
 
 export 'src/services/activity.dart';

packages/flutter/lib/src/animation/README.md

-This directory contains animation-related libraries that only depend
-on core Dart libraries and the Newton Dart library.

packages/flutter/lib/src/material/README.md

-This directory provides constants for Material Design.
-
-   http://www.google.com/design/spec/material-design/
-
-Files in this directory only depend on [painting.dart](../../painting.dart) and
-`sky:dart`.

packages/flutter/lib/src/painting/README.md

-This directory contains painting-related libraries that only depend on
-core Dart libraries and [animation.dart](../../animation.dart). Note
-that [animation.dart](../../animation.dart) depends on the Newton Dart library.

packages/flutter/lib/src/services/README.md

-This directory contains code for exposing mojo services to Sky apps.
-For example, keyboard.dart wraps the mojo keyboard service in a more
-convenient Dart class.
-
-Files in this directory (and its subdirectories) only depend on core
-Dart libraries, `dart:sky`, `dart:sky.internals`, the `mojo` package,
-and the `mojo_services` package.

packages/flutter/lib/widgets.dart

@@ -2,9 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-/// The Sky widget framework.
-///
-/// This library includes and re-exports all Sky widgets classes.
+/// The Flutter widget framework.
 library widgets;
 
 export 'package:sky/src/widgets/animated_component.dart';