Update styling-the-navigator.md

docs/styling-the-navigator.md

   collapsingToolBarImage: "http://lorempixel.com/400/200/", // Collapsing Toolbar image.
   collapsingToolBarImage: require('../../img/topbar.jpg'), // Collapsing Toolbar image. Either use a url or require a local image.
   collapsingToolBarCollapsedColor: '#0f2362', // Collapsing Toolbar scrim color.
+  navBarTextFontBold: false, // Optional. Set the title to bold.
+  navBarHeight: 70, // Optional, set the navBar height in pixels.
+  topTabsHeight: 70, // Optional, set topTabs height in pixels.
 }
 ```