Add forceTitlesDisplay to docs (#1091)

docs/styling-the-tab-bar.md

   tabBarBackgroundColor: '#551A8B' // change the background color of the tab bar
   tabBarTranslucent: false // change the translucent of the tab bar to false
   tabBarTextFontFamily: 'Avenir-Medium' //change the tab font family
+  forceTitlesDisplay: true // Android only. If true - Show all bottom tab labels. If false - only the selected tab's label is visible.
 }
 ```
 
 ...
 }
 ```
-
-All supported styles are defined [here](https://github.com/wix/react-native-controllers#styling-tab-bar). There's also an example project there showcasing all the different styles.