Fixed flash size for AZ-Delivery ESP-32 Dev Kit C V4

Resolves platformio/platformio-docs#234

Author: valeros

boards/az-delivery-devkit-v4.json

@@ -28,7 +28,7 @@
   "upload": {
     "flash_size": "4MB",
     "maximum_ram_size": 532480,
-    "maximum_size": 16777216,
+    "maximum_size": 4194304,
     "require_upload_port": true,
     "speed": 460800
   },