Starting VOLTHA 2.9 docs

Change-Id: Ie2e3fe80eb47419c17931d15666f2bce69de8dfc
diff --git a/VERSION b/VERSION
index dbe5900..ffd8a2b 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.8.1
+2.9.0-dev