add traffic_calming field to minor and major road presets

data/fields/traffic_calming_road.json

@@ -0,0 +1,20 @@
+{
+    "key": "traffic_calming",
+    "type": "typeCombo",
+    "label": "Traffic Calming",
+    "terms": [
+        "bump",
+        "chicane",
+        "choker",
+        "cushion",
+        "flat top",
+        "hump",
+        "rumble strip",
+        "slow",
+        "speed",
+        "table",
+        "traffic island"
+    ],
+    "stringsCrossReference": "{traffic_calming}",
+    "iconsCrossReference": "{traffic_calming}"
+}