Add missing SPDX header.

Author: cpyle0819

javascriptv3/example_code/cross-services/textract-react/src/Config.js

@@ -1,3 +1,6 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
 export const Config = {
   ConfigError:
     "Demo resources not initialized. You must deploy AWS resources and demo elements before running this application. See the README for details.",