Clean up BottomBar docs

Test: made sure docs target build, results looked reasonable
Bug: 32270959 clean up example in BottomNavigationView header docs
Change-Id: Ie27b07ae6b34da60942b448e61386f0a254691e5
diff --git a/design/src/android/support/design/widget/BottomNavigationView.java b/design/src/android/support/design/widget/BottomNavigationView.java
index 1d36aa8..e82f1fb 100644
--- a/design/src/android/support/design/widget/BottomNavigationView.java
+++ b/design/src/android/support/design/widget/BottomNavigationView.java
@@ -56,14 +56,28 @@
  * </p>
  *
  * <pre>
+ * layout resource file:
  * &lt;android.support.design.widget.BottomNavigationView
  *     xmlns:android="http://schemas.android.com/apk/res/android"
  *     xmlns:design="http://schema.android.com/apk/res/android.support.design"
  *     android:id="@+id/navigation"
- *     android:layout_width="wrap_content"
- *     android:layout_height="match_parent"
+ *     android:layout_width="match_parent"
+ *     android:layout_height="56dp"
  *     android:layout_gravity="start"
  *     design:menu="@menu/my_navigation_items" /&gt;
+ *
+ * res/menu/my_navigation_items.xml:
+ * &lt;menu xmlns:android="http://schemas.android.com/apk/res/android"&gt;
+ *     &lt;item android:id="@+id/action_search"
+ *          android:title="@string/menu_search"
+ *          android:icon="@drawable/ic_search" /&gt;
+ *     &lt;item android:id="@+id/action_settings"
+ *          android:title="@string/menu_settings"
+ *          android:icon="@drawable/ic_add" /&gt;
+ *     &lt;item android:id="@+id/action_navigation"
+ *          android:title="@string/menu_navigation"
+ *          android:icon="@drawable/ic_action_navigation_menu" /&gt;
+ * &lt;/menu&gt;
  * </pre>
  */
 public class BottomNavigationView extends FrameLayout {