Update map_transitions_and_warps.md

docs/events/map_transitions_and_warps.md

@@ -111,3 +111,6 @@ Note: If you touch CROSS MAP OFF, the next warp stone will not warp you to a dif
   
 Note: Direct warps are disabled if the computer room background is used in the room. It is disabled until you trigger the event that activates the computer room.
 
+# Doors
+
+Doors are created simply by placing event 80 or 81 just above the floor.  Doors will warp the player exactly two screens upwards (event 80) or downwards (event 81).