Also add new setting to expert.

part of CURA-10829

resources/setting_visibility/expert.cfg

@@ -60,6 +60,7 @@ skin_monotonic
 connect_skin_polygons
 skin_angles
 small_skin_width
+small_skin_on_surface
 skin_no_small_gaps_heuristic
 skin_outline_count
 ironing_enabled