Add authors and copyright to reference doc

Issue gh-1295

Author: jgrandja

docs/modules/ROOT/pages/index.adoc

@@ -10,3 +10,9 @@ xref:configuration-model.adoc[Configuration Model] :: Default configuration and
 xref:core-model-components.adoc[Core Model / Components] :: Core domain model and component interfaces
 xref:protocol-endpoints.adoc[Protocol Endpoints] :: OAuth2 and OpenID Connect 1.0 protocol endpoint implementations
 xref:how-to.adoc[How-to Guides] :: Guides to get the most from Spring Authorization Server
+
+Joe Grandja, Steve Riesenberg
+
+Copyright © 2020 - 2023
+
+Copies of this document may be made for your own use and for distribution to others, provided that you do not charge any fee for such copies and further provided that each copy contains this Copyright Notice, whether distributed in print or electronically.