tweaked metafield name

Author: nickwesselman

sample-apps/discounts/extensions/product-discount/input.graphql

@@ -11,7 +11,7 @@ query Input {
     }
   }
   discountNode {
-    metafield(namespace: "$app:discounts-tutorial", key: "function-configuration") {
+    metafield(namespace: "$app:volume-discount", key: "function-configuration") {
       value
     }
   }

sample-apps/discounts/web/frontend/pages/volume/[functionId]/new.jsx

@@ -29,7 +29,7 @@ import { data } from "@shopify/app-bridge/actions/Modal";
 import { useAuthenticatedFetch } from "../../../hooks";
 
 const todaysDate = new Date();
-const METAFIELD_NAMESPACE = "$app:discounts-tutorial";
+const METAFIELD_NAMESPACE = "$app:volume-discount";
 const METAFIELD_CONFIGURATION_KEY = "function-configuration";
 
 export default function VolumeNew() {