docs: Fixing Android TV code snippet

Changing code snippet to use FullWidthDetailsOverviewRowPresenter
instead of DetailsOverviewRowPresenter (which is deprecated).
Verified code snippet change by checking and building it in
Android Studio using an unrelated sample.

Bug: 25666843
Change-Id: I6db32a570757b7f8f1f848f7579b29617ffb18d6

docs/html/training/tv/playback/details.jd

@@ -111,8 +111,9 @@ public class MediaItemDetailsFragment extends DetailsFragment {
     private void buildDetails() {
         ClassPresenterSelector selector = new ClassPresenterSelector();
         // Attach your media item details presenter to the row presenter:
-        DetailsOverviewRowPresenter rowPresenter =
-            new DetailsOverviewRowPresenter(new DetailsDescriptionPresenter());
+        FullWidthDetailsOverviewRowPresenter rowPresenter =
+            new FullWidthDetailsOverviewRowPresenter(
+                new DetailsDescriptionPresenter());
 
         selector.addClassPresenter(DetailsOverviewRow.class, rowPresenter);
         selector.addClassPresenter(ListRow.class,