Update search bar's navup content description

It should read "Search settings"

Change-Id: I1a55f905949341b290ea5f224171592cf5021e31
Fix: 64140213
Test: talkback
diff --git a/res/layout/settings_main_dashboard.xml b/res/layout/settings_main_dashboard.xml
index 95299ae..8e83cff 100644
--- a/res/layout/settings_main_dashboard.xml
+++ b/res/layout/settings_main_dashboard.xml
@@ -42,6 +42,7 @@
                 android:background="?android:attr/selectableItemBackground"
                 android:contentInsetStartWithNavigation="64dp"
                 android:navigationIcon="@drawable/ic_search_24dp"
+                android:navigationContentDescription="@string/search_menu"
                 android:title="@string/search_menu"
                 android:titleTextAppearance="@style/TextAppearance.SearchBar"
                 android:theme="?android:attr/actionBarTheme"/>