new documentation - tabBarOptions keyboardHidesTabBar (react-navigation#439)

* new documentation - tabBarOptions keyboardHidesTabBar

referencing: https://github.com/react-navigation/tabs/issues/16#issuecomment-485027123

Author: brentvatne

docs/bottom-tab-navigator.md

@@ -51,6 +51,7 @@ The route configs object is a mapping from route name to a route config, which t
   * `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.
   * `safeAreaInset` - Override the `forceInset` prop for `<SafeAreaView>`. Defaults to `{ bottom: 'always', top: 'never' }`. Available keys are `top | bottom | left | right` provided with the values `'always' | 'never'`.
+  * `keyboardHidesTabBar` - Defaults to `false`. If `true` hide the tab bar when keyboard opens.
 
 Example:
 

website/versioned_docs/version-3.x/bottom-tab-navigator.md

@@ -42,6 +42,7 @@ The route configs object is a mapping from route name to a route config, which t
   * `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.
   * `safeAreaInset` - Override the `forceInset` prop for `<SafeAreaView>`. Defaults to `{ bottom: 'always', top: 'never' }`. Available keys are `top | bottom | left | right` provided with the values `'always' | 'never'`.
+  * `keyboardHidesTabBar` - Defaults to `false`. If `true` hide the tab bar when keyboard opens.
 
 Example: