Define both gridDistance and grid.distance to maintain backwards comp…

…atibility with v11 and remove warnings from v12

system/system.json

@@ -298,10 +298,14 @@
 			]
 		}
 	],
+    "grid": {
+        "distance": 5,
+        "units": "ft"
+    },
+    "gridDistance": 5,
+    "gridUnits": "ft",
 	"socket": true,
-	"gridDistance": 5,
 	"initiative": "@initiativeFormula + @initiativeBonus",
 	"primaryTokenAttribute": "attributes.hp",
-	"gridUnits": "ft",
 	"background": "systems/shadowdark/assets/artwork/GM_Screen_Final_Drawing_Elongated.webp"
 }