Adding the Voltha missing manual

Change-Id: Ic6cc2e5ed80e04fb009809c9a2fca393e5dcabfd
diff --git a/.gitignore b/.gitignore
index 5518b83..7aac286 100644
--- a/.gitignore
+++ b/.gitignore
@@ -71,3 +71,8 @@
 
 # Vagrant logfile
 *.log
+
+# gitnook artifacts
+docs/manuals/user/_book
+docs/manual/user/*.pdf
+docs/manual/user/node_modules