Merge "Add readme to ApiDemos to mention the need for android-support-v4"

samples/ApiDemos/README.txt

@@ -0,0 +1,19 @@
+The API Demos application includes a variety of small applications 
+that illustrate the use of various Android APIs. It includes samples of:
+  - Notifications
+  - Alarms
+  - Progress Dialogs
+  - Intents
+  - Menus
+  - Search
+  - Persistent application state
+  - Preferences
+  - Background Services
+  - App Widgets
+  - Voice Recognition
+  - And many many more...
+
+Api demos is designed to use the compatibility library "android-support-v4.jar".
+It is available through the SDK Updater in the "Android Compatibility package".
+Once downloaded, copy the jar file into the ApiDemos project libs/ folder.
+(If using Eclipse, add it manually to the project build path).