[feat] update payload examples

events/payload_point.json

@@ -1,6 +1,8 @@
 {
-  "ne": {"lat": 45.699, "lng": 127.1},
-  "sw": {"lat": 30.1, "lng": 148.492},
+  "bbox": {
+    "ne": {"lat": 45.699, "lng": 127.1},
+    "sw": {"lat": 30.1, "lng": 148.492}
+  },
   "prompt": [{
     "type": "point",
     "data": {"lat": 36.91, "lng": 136.854},

events/payload_point2.json

@@ -1,6 +1,8 @@
 {
-  "ne": {"lat": 38.03932961278458, "lng": 15.36808069832851},
-  "sw": {"lat": 37.455509218936974, "lng":  14.632807441554068},
+  "bbox": {
+    "ne": {"lat": 38.03932961278458, "lng": 15.36808069832851},
+    "sw": {"lat": 37.455509218936974, "lng":  14.632807441554068}
+  },
   "prompt": [{
     "type": "point",
     "data": {"lat": 37.0, "lng": 15.0},