Add banner and icons to the update.json (#35)

Co-authored-by: Joe Worthington <joe@pie.co.de>

Author: Joseph-Worthington

assets/banners/banner-1544x500.png

@@ -2,6 +2,15 @@
     "name": "Pie Custom Functions",
     "version": "1.1.0",
     "download_url": "https://github.com/pie/pie-custom-functions/releases/download/1.1.0/pie-custom-functions.zip",
+    "banners": {
+        "low" : "./assets/banners/banner-772x225.png",
+        "high" : "./assets/banners/banner-1544x500.png"
+    },
+    "icons": {
+        "1x" : "./assets/icons/icon-128x128.png",
+        "2x" : "./assets/icons/icon-256x256.png",
+        "svg" : "./assets/icons/icon.svg"
+    },
     "sections": {
         "description" : "Custom functions for Pie Hosting"
     }