[UI/UX] Remove bottom margin of General tab (Settings)

The bottom margin (little gap) under General tab of Settings
make it hard to "feel" the space is scrollable or not.

New windows style and websites tend to not have margin in the bottom

Related to: Issue #443 and PR #440

Author: pc223

Flow.Launcher/SettingWindow.xaml

@@ -36,7 +36,7 @@
 
     <TabControl Height="auto" SelectedIndex="0">
         <TabItem Header="{DynamicResource general}">
-            <ScrollViewer ui:ScrollViewerHelper.AutoHideScrollBars="{Binding AutoHideScrollBar, Mode=OneWay}" Margin="60,30,0,30">
+            <ScrollViewer ui:ScrollViewerHelper.AutoHideScrollBars="{Binding AutoHideScrollBar, Mode=OneWay}" Margin="60,30,0,0">
                 <StackPanel Orientation="Vertical">
                     <ui:ToggleSwitch Margin="10" IsOn="{Binding PortableMode}">
                         <TextBlock Text="{DynamicResource portableMode}" />