Expand screen documentation with explicit screen size dimensions.

This updates the various documentation on screen sizes to discuss
the exact screen dimensions that are now associated with each size.
In addition, the screen sizes vs. densities table is updated to
include a number of additional representative screens.

Change-Id: Id07491148b1857e0265cef7139e564e190f38e03
diff --git a/core/java/android/content/res/Configuration.java b/core/java/android/content/res/Configuration.java
index 31119d7..72fa07c 100644
--- a/core/java/android/content/res/Configuration.java
+++ b/core/java/android/content/res/Configuration.java
@@ -57,11 +57,30 @@
      */
     public boolean userSetLocale;
 
+    /** Constant for {@link #screenLayout}: bits that encode the size. */
     public static final int SCREENLAYOUT_SIZE_MASK = 0x0f;
+    /** Constant for {@link #screenLayout}: a {@link #SCREENLAYOUT_SIZE_MASK}
+     * value indicating that no size has been set. */
     public static final int SCREENLAYOUT_SIZE_UNDEFINED = 0x00;
+    /** Constant for {@link #screenLayout}: a {@link #SCREENLAYOUT_SIZE_MASK}
+     * value indicating the screen is at least approximately 320x426 dp units.
+     * See <a href="{@docRoot}guide/practices/screens_support.html">Supporting
+     * Multiple Screens</a> for more information. */
     public static final int SCREENLAYOUT_SIZE_SMALL = 0x01;
+    /** Constant for {@link #screenLayout}: a {@link #SCREENLAYOUT_SIZE_MASK}
+     * value indicating the screen is at least approximately 320x470 dp units.
+     * See <a href="{@docRoot}guide/practices/screens_support.html">Supporting
+     * Multiple Screens</a> for more information. */
     public static final int SCREENLAYOUT_SIZE_NORMAL = 0x02;
+    /** Constant for {@link #screenLayout}: a {@link #SCREENLAYOUT_SIZE_MASK}
+     * value indicating the screen is at least approximately 480x640 dp units.
+     * See <a href="{@docRoot}guide/practices/screens_support.html">Supporting
+     * Multiple Screens</a> for more information. */
     public static final int SCREENLAYOUT_SIZE_LARGE = 0x03;
+    /** Constant for {@link #screenLayout}: a {@link #SCREENLAYOUT_SIZE_MASK}
+     * value indicating the screen is at least approximately 720x960 dp units.
+     * See <a href="{@docRoot}guide/practices/screens_support.html">Supporting
+     * Multiple Screens</a> for more information.*/
     public static final int SCREENLAYOUT_SIZE_XLARGE = 0x04;
     
     public static final int SCREENLAYOUT_LONG_MASK = 0x30;
@@ -88,6 +107,9 @@
      * <p>The {@link #SCREENLAYOUT_LONG_MASK} defines whether the screen
      * is wider/taller than normal.  They may be one of
      * {@link #SCREENLAYOUT_LONG_NO} or {@link #SCREENLAYOUT_LONG_YES}.
+     * 
+     * <p>See <a href="{@docRoot}guide/practices/screens_support.html">Supporting
+     * Multiple Screens</a> for more information.
      */
     public int screenLayout;