Update gameTables.lua (#508)

On an XBox controller, B is on the right and A is on the bottom (unlike a Nintendo controller), and it makes more sense to default B to rotate right and A to rotate left.

parts/gameTables.lua

@@ -675,7 +675,7 @@ do--Userdata tables
             r=0,
         },
         joystick={
-            dpleft=1,dpright=2,a=3,b=4,y=5,
+            dpleft=1,dpright=2,b=3,a=4,y=5,
             dpup=6,dpdown=7,rightshoulder=8,x=9,
             leftshoulder=0,
         },
@@ -722,4 +722,4 @@ do--Userdata tables
         date=false,
         todayTime=0,
     }
-end
+end