Update default.cfg

found this from zer0Kerbal/Komplexity#39
* add a little helpful information
* make match stock
  * runway
![image](https://user-images.githubusercontent.com/39887717/163516438-8d8ad49c-7511-41dd-baf5-77db267b77f7.png)
  * launchpad
![engineeringReport-VAB](https://user-images.githubusercontent.com/39887717/163519231-e0d6c359-9263-43ee-af13-f3d1f2712b95.png)

CustomBarnKit/default.cfg

@@ -31,8 +31,9 @@ CUSTOMBARNKIT
 		craftMassLimit = 18, 140, -1
 		craftSizeLimit
 		{
-			size = 15, 20, 15
-			size = 28, 36, 28
+		// width, height, length
+			size = 20, 15, 15
+			size = 36, 28, 28
 			size = -1, -1, -1
 		}
 		useBuilding = false
@@ -46,8 +47,9 @@ CUSTOMBARNKIT
 		craftMassLimit = 18, 140, -1
 		craftSizeLimit
 		{
-			size = 15, 20, 15
-			size = 28, 36, 28
+		// width, height, length
+			size = 20, 15, 15
+			size = 36, 28, 28
 			size = -1, -1, -1
 		}
 		useBuilding = false
@@ -151,4 +153,4 @@ CUSTOMBARNKIT
 		unlockedFuelTransfer = 2
 	}
 
-}
+}