[MIRROR] fixes documentation and overlays on catwalks [MDB IGNORE] (#8655)

* catwalks with fixed documentation and overlays (#61916)

corrects documentation in layers.dm and catwalk_plating.dm. catwalks now correctly hide what's under them with the overlay. catwalk under plating now has a naked sprite instead of still showing the over-plating (which was confusing in game). also adds a built overlay example to that file.

* fixes documentation and overlays on catwalks

Co-authored-by: tralezab <40974010+tralezab@users.noreply.github.com>

code/__DEFINES/layers.dm

@@ -44,7 +44,7 @@
 #define GAS_FILTER_LAYER 2.48
 #define GAS_PUMP_LAYER 2.49
 #define LOW_OBJ_LAYER 2.5
-///catwalk overlay of /turf/open/floor/plating/plating_catwalk
+///catwalk overlay of /turf/open/floor/plating/catwalk_floor
 #define CATWALK_LAYER 2.51
 #define LOW_SIGIL_LAYER 2.52
 #define SIGIL_LAYER 2.54

code/game/turfs/open/floor/catwalk_plating.dm

@@ -2,7 +2,7 @@
  * ## catwalk flooring
  *
  * They show what's underneath their catwalk flooring (pipes and the like)
- * you can crowbar it to interact with the underneath stuff without destroying the tile...
+ * you can screwdriver it to interact with the underneath stuff without destroying the tile...
  * unless you want to!
  */
 /turf/open/floor/plating/catwalk_floor
@@ -23,9 +23,14 @@
 
 /turf/open/floor/plating/catwalk_floor/update_overlays()
 	. = ..()
-	var/static/catwalk_overlay
+	var/static/image/catwalk_overlay
 	if(isnull(catwalk_overlay))
-		catwalk_overlay = iconstate2appearance(icon, "catwalk_above")
+		catwalk_overlay = new()
+		catwalk_overlay.icon = icon
+		catwalk_overlay.icon_state = "catwalk_above"
+		catwalk_overlay.plane = GAME_PLANE
+		catwalk_overlay.layer = CATWALK_LAYER
+		catwalk_overlay = catwalk_overlay.appearance
 	if(covered)
 		. += catwalk_overlay