Twelve: Set navigation rail gravity to center

Matches figma and Material guidelines

Change-Id: I2d1a3b1ea70e1ad88102558f359cf6811a149227
diff --git a/app/src/main/res/layout-land/fragment_main.xml b/app/src/main/res/layout-land/fragment_main.xml
index 72bc605..8df5917 100644
--- a/app/src/main/res/layout-land/fragment_main.xml
+++ b/app/src/main/res/layout-land/fragment_main.xml
@@ -65,7 +65,7 @@
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toTopOf="parent"
         app:menu="@menu/navigation_bar_view_fragment_main"
-        app:menuGravity="top"
+        app:menuGravity="center"
         app:paddingBottomSystemWindowInsets="false"
         app:paddingTopSystemWindowInsets="false" />