Document useBottomTabBarHeight

Author: satya164

versioned_docs/version-5.x/bottom-tab-navigator.md

@@ -237,7 +237,39 @@ Takes an object containing following optional properties:
 
 ##### `style`
 
-Style object for the tab bar.
+Style object for the tab bar. You can configure styles such as background color here.
+
+To show your screen under the tab bar, you can set the `position` style to absolute:
+
+```js
+style: { position: 'absolute' }
+```
+
+You also might need to add a bottom margin to your content if you have a absolutely positioned tab bar. React Navigation won't do it automatically.
+
+To get the height of the bottom tab bar, you can use `BottomTabBarHeightContext` with [React's Context API](https://reactjs.org/docs/context.html#contextconsumer) or `useBottomTabBarHeight`:
+
+```js
+import { BottomTabBarHeightContext } from '@react-navigation/bottom-tabs';
+
+// ...
+
+<BottomTabBarHeightContext.Consumer>
+  {tabBarHeight => (
+    /* render something */
+  )}
+</BottomTabBarHeightContext.Consumer>
+```
+
+or
+
+```js
+import { useBottomTabBarHeight } from '@react-navigation/bottom-tabs';
+
+// ...
+
+const tabBarHeight = useBottomTabBarHeight();
+```
 
 ### Options