added documentation links

Author: Peter Leibiger

picasso/src/main/java/com/squareup/picasso/Target.java

@@ -40,18 +40,18 @@ public interface Target {
   /**
    * Callback indicating the image could not be successfully loaded.
    * <p/>
-   * <strong>Note:</strong> The passed Drawable may be null if none has been specified
-   * via {@link RequestCreator#error(android.graphics.drawable.Drawable)}
+   * <strong>Note:</strong> The passed {@link Drawable} may be {@code null} if none has been
+   * specified via {@link RequestCreator#error(android.graphics.drawable.Drawable)}
    * or {@link RequestCreator#error(int)}.
    */
   void onBitmapFailed(Drawable errorDrawable);
 
   /**
-  * Callback invoked right before your request is submitted.
-  * <p/>
-  * <strong>Note:</strong> The passed Drawable may be null if none has been specified
-  * via {@link RequestCreator#placeholder(android.graphics.drawable.Drawable)}
-  * or {@link RequestCreator#placeholder(int)}.
-  */
+   * Callback invoked right before your request is submitted.
+   * <p/>
+   * <strong>Note:</strong> The passed {@link Drawable} may be {@code null} if none has been
+   * specified via {@link RequestCreator#placeholder(android.graphics.drawable.Drawable)}
+   * or {@link RequestCreator#placeholder(int)}.
+   */
   void onPrepareLoad(Drawable placeHolderDrawable);
 }