update umbraco demo

Author: skttl

src/demos/RemoteImageProviderUmbracoDemo/RemoteProviderComposer.cs

@@ -11,6 +11,17 @@
     }
   },
   "Umbraco": {
+    "Community": {
+      "ImageSharpRemoteImages": {
+        "Settings": [
+          {
+            "Prefix": "/ourumb",
+            "AllowedDomains": [ "https://our.umbraco.com" ],
+            "RemoteUrlPrefix": "https://our.umbraco.com"
+          }
+        ]
+      }
+    },
     "CMS": {
       "Global": {
         "Id": "c84e1fac-e971-46e5-901f-c64c2cddc63d",