Update styling.md (#3509)

`largeTitle: true` is not valid and throws error

docs/docs/styling.md

     buttonColor: 'black',
     drawBehind: false,
     testID: 'topBar',
-    largeTitle: true, // iOS 11+ Large Title
     searchBar: true, // iOS 11+ native UISearchBar inside topBar
     searchBarHiddenWhenScrolling: true,
     searchBarPlaceholder: 'Search', // iOS 11+ SearchBar placeholder
+    // iOS 11+ Large Title
     largeTitle: {
       visible: true,
       fontSize: 30,