Release notes for voltha-2.9 and adding bandwidth profile documentation

Change-Id: I3bd3857da7aadf577133be5228d611984b129faa
diff --git a/VERSION b/VERSION
index ffd8a2b..c8e38b6 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.9.0-dev
+2.9.0