Update MainPage.xaml

Make NetWork flyout readable by Narrator

src/App/MainPage.xaml

@@ -30,6 +30,14 @@
                     </StackPanel>
                     <Button.Flyout>
                         <Flyout x:Name="NetworkFlyout" Opening="NetworkFlyout_Opening">
+                            <Flyout.FlyoutPresenterStyle>
+                                <Style TargetType="FlyoutPresenter">
+                                    <Setter Property="ScrollViewer.HorizontalScrollMode" Value="Disabled"/>
+                                    <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Disabled"/>
+                                    <Setter Property="IsTabStop" Value="True"/>
+                                    <Setter Property="TabNavigation" Value="Cycle"/>
+                                </Style>
+                            </Flyout.FlyoutPresenterStyle>
                             <StackPanel Orientation="Vertical" HorizontalAlignment="Center">
                                 <TextBlock Style="{StaticResource FlyoutPickerTitleTextBlockStyle}" x:Uid="IpHeader" HorizontalAlignment="Center"/>
                                 <StackPanel x:Name="NetworkStackPanel" Orientation="Vertical" HorizontalAlignment="Center">