gui2/title_screen: Increase bottom row margins from 0px to 10px

This hopefully makes it seem a little tidier than having all of the
bottom row buttons and labels hugging the edges of the game screen.

data/gui/window/title_screen.cfg

@@ -449,6 +449,8 @@ where
 				[column]
 					horizontal_grow = true
 					vertical_alignment = "bottom"
+					border = "bottom,left,right"
+					border_size = 10
 
 					[grid]