Set up export button to export a simple file

app.js

@@ -4,8 +4,10 @@ import Home from './components/home'
 import Calendar from './components/calendar'
 import CycleDay from './components/cycle-day'
 import Chart from './components/chart/chart'
+import Settings from './components/settings'
 
-// this is until react native fixes this bug, see https://github.com/facebook/react-native/issues/18868#issuecomment-382671739
+// this is until react native fixes this bugg, see
+// https://github.com/facebook/react-native/issues/18868#issuecomment-382671739
 import { YellowBox } from 'react-native'
 YellowBox.ignoreWarnings(['Warning: isMounted(...) is deprecated'])
 
@@ -13,5 +15,6 @@ export default createStackNavigator({
   home: { screen: Home },
   calendar: { screen: Calendar },
   cycleDay: { screen: CycleDay },
-  chart: { screen: Chart }
+  chart: { screen: Chart },
+  settings: { screen: Settings }
 })