Add license header

Author: reakaleek

src/docs-builder/LinkIndex/ILinkIndex.cs

@@ -1,3 +1,6 @@
+// Licensed to Elasticsearch B.V under one or more agreements.
+// Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information
 namespace Documentation.Builder.LinkIndex;
 
 public interface ILinkIndex

src/docs-builder/LinkIndex/S3LinkIndex.cs

@@ -1,7 +1,9 @@
+// Licensed to Elasticsearch B.V under one or more agreements.
+// Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information
 using Amazon.S3;
 using Amazon.S3.Transfer;
 using Microsoft.Extensions.Logging;
-using Microsoft.Extensions.Configuration;
 
 namespace Documentation.Builder.LinkIndex;