Bump top spacing for action buttons

Author: donokuda

src/GitHub.VisualStudio/Views/Dialog/ForkRepositoryExecuteView.xaml

@@ -70,7 +70,7 @@
                 </Grid>
         </Border>
 
-        <StackPanel Orientation="Vertical" Margin="0 8 0 0">
+        <StackPanel Orientation="Vertical" Margin="0 16 0 0">
             <StackPanel HorizontalAlignment="Right" Orientation="Horizontal">
               <Button Margin="0 0 4 0">Back</Button>
               <Button Click="repoForkButton_OnClick">Fork Repo</Button>