Docs changes pursuant to API review feedback.

Change-Id: I74c51791192f7fefad4e299d25c91438cbf6ab73

core/java/android/database/Cursor.java

@@ -25,9 +25,12 @@ import java.io.Closeable;
 /**
  * This interface provides random read-write access to the result set returned
  * by a database query.
- *
+ * <p>
  * Cursor implementations are not required to be synchronized so code using a Cursor from multiple
  * threads should perform its own synchronization when using the Cursor.
+ * </p><p>
+ * Implementations should subclass {@link AbstractCursor}.
+ * </p>
  */
 public interface Cursor extends Closeable {
     /*