Update web readme (#79)

web/readme.md

@@ -1,14 +1,22 @@
 Samples for [Flutter for web](https://flutter.dev/web).
 
-#### Building Samples code
-Set up `webdev` for first time as below:
-```
-$ pub global activate webdev
-$ pub get
-```
+## See the samples in action
 
-Build and run code locally at `http://localhost:8080`
-```
+Compiled versions of the samples are hosted at [flutter.github.io/samples](https://flutter.github.io/samples/).
+
+## Building samples code
+
+Make sure you have configured the `webdev` tool.
+
+- [With the Flutter SDK installed](https://github.com/flutter/flutter_web#install-the-flutter_web-build-tools).
+- [With the Dart SDK installed](https://dart.dev/tools/webdev#using-webdev-and-build_runner-commands).
+
+Go into one of the sample directories, get packages, and run.
+
+```console
+$ cd gallery
+$ flutter packages pub get # or `pub get` with the Dart SDK
 $ webdev serve
 ```
-Checkout [this link](https://dart.dev/tools/webdev#using-webdev-and-build_runner-commands) for more details about building, serving and testing code.
+
+You should see a message printing the URL to access: `http://localhost:8080`