Update bottom-tab-navigator.md (#860)

Co-authored-by: Satyajit Sahoo <satyajit.happy@gmail.com>

versioned_docs/version-4.x/bottom-tab-navigator.md

@@ -47,7 +47,7 @@ The route configs object is a mapping from route name to a route config, which t
   - `showIcon` - Whether to show icon for tab, default is true.
   - `style` - Style object for the tab bar.
   - `labelStyle` - Style object for the tab label.
-  - `labelPosition` - Where to show the tab label in relation to the tab icon. Available values are `beside-icon` and `below-icon`. Defaults to `beside-icon`.
+  - `labelPosition` - Where to show the tab label in relation to the tab icon. Available values are `beside-icon` and `below-icon`. Defaults to `below-icon` on mobile and `beside-icon` on tablets.
   - `tabStyle` - Style object for the tab.
   - `allowFontScaling` - Whether label font should scale to respect Text Size accessibility settings, default is true.
   - `adaptive` - Should the tab icons and labels alignment change based on screen size? Defaults to `true` for iOS 11. If `false`, tab icons and labels align vertically all the time. When `true`, tab icons and labels align horizontally on tablet.