[VOL-5545] Update voltha docs

- release notes for VOLTHA versions 2.6 to 2.15 with new Jira links and adjust release schedule details
- update old links
- remove ONF references and links
- update e-mail links
- update copright notices

Change-Id: Id6be18986a8f52f2dfcc07e2b0d2efcb0ae1c0e4
Signed-off-by: serkant.uluderya <serkant.uluderya@netsia.com>
diff --git a/resources/sources/voltha.gerrit b/resources/sources/voltha.gerrit
index f7e5c46..053596b 100644
--- a/resources/sources/voltha.gerrit
+++ b/resources/sources/voltha.gerrit
@@ -1,5 +1,5 @@
 ## -----------------------------------------------------------------------
-## Copyright 2021-2023 Open Networking Foundation (ONF) and the ONF Contributors
+## Copyright 2021-2023 Linux Foundation Broadband Contributors
 ##
 ## Licensed under the Apache License, Version 2.0 (the "License");
 ## you may not use this file except in compliance with the License.