missed header

Author: brettsam

src/WebJobs.Script.WebHost/Security/KeyManagement/ContainerAppsSecretsRepository.cs

@@ -1,4 +1,7 @@
-using System;
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;