[animations] README updates (#90)

* Update README with new examples

* Add pointer to the sample app in README

* Remove heavy development notice on README

packages/animations/README.md

@@ -1,15 +1,50 @@
 # Fancy pre-built Animations for Flutter
 
-**This package is still under heavy development and may change frequently.**
-
 This package contains pre-canned animations for commonly-desired effects. The animations can be customized with your content and dropped into your application to delight your users.
 
+To see examples of the following animations on a device or simulator:
+
+```bash
+cd example/
+flutter run --release
+```
+
 ## Available Animations
 
 Currently, the following animated effects are available in this library:
 
-### Material's [Open Container Transitions](https://material.io/design/motion/choreography.html#transformation)
+### Material's Open Container Transitions
+
+Tapping on a container (e.g. a card or a button) will expand the container to reveal more information.
+
+| Card with Fade Transition           |  Card with Fade Through Transition  |
+:------------------------------------:|:------------------------------------:
+|![Open Container Card Fade Transition Demo](example/demo_gifs/open_container_fade_card_demo.gif)|![Open Container Card Fade Through Transition Demo](example/demo_gifs/open_container_fade_through_card_demo.gif)
+| **Floating Action Button with Fade Transition**          |  **Floating Action Button with Fade Through Transition** |
+|![Open Container Card Fade Transition Demo](example/demo_gifs/open_container_fade_floating_action_button_demo.gif)|![Open Container Floating Action Button Fade Through Transition Demo](example/demo_gifs/open_container_fade_through_floating_action_button_demo.gif)
+### Material's Shared Axis Transitions
+
+A transition animation between UI elements that have a spatial or navigational
+relationship.
+
+| Horizontal (x-axis)      |  Vertical (y-axis)      | Scaled (z-axis)      |
+:-------------------------:|:-----------------------:|:--------------------:|
+|![Shared Axis Horizontal Transition Demo](example/demo_gifs/shared_axis_horizontal_demo.gif)|![Shared Axis Vertical Transition Demo](example/demo_gifs/shared_axis_vertical_demo.gif)|![Shared Axis Scaled Transition Demo](example/demo_gifs/shared_axis_scaled_demo.gif)
+
+### Material's Fade Through Transition
+
+A transition animation between UI elements that have do not have a strong
+relationship to one another.
+
+| Fade Through Page Transition |
+:-----------------------------:|
+|![Fade Through Transition Demo](example/demo_gifs/fade_through_demo.gif)|
+
+### Material's Fade Transition
 
-Tapping on a container  (e.g. a card or a button) will expand the container to reveal more information.
+The fade pattern is used for UI elements that enter or exit from within
+the screen bounds.
 
-*TODO(goderbauer): Add example videos of this effect.*
+| Modal Fade Transition             |  Floating Action Button Fade Transition |
+:----------------------------------:|:----------------------------------------:
+|![Fade Modal Transition Demo](example/demo_gifs/fade_modal_demo.gif)|![Fade Floating Action Button Transition Demo](example/demo_gifs/fade_floating_action_button_demo.gif)

packages/animations/example/README.md

@@ -1,3 +1,3 @@
-# Example Catalog fir package:animations.
+# Example Catalog for package:animations.
 
 Run `flutter run --release` in this directory to launch the catalog on a device.

packages/animations/lib/src/shared_axis_transition.dart

@@ -28,7 +28,6 @@ enum SharedAxisTransitionType {
 /// that have a spatial or navigational relationship. For example,
 /// transitioning from one page of a sign up page to the next one.
 ///
-///
 /// The following example shows how the SharedAxisPageTransitionsBuilder can
 /// be used in a [PageTransitionsTheme] to change the default transitions
 /// of [MaterialPageRoute]s.