adding operating guide

Change-Id: I6b77fc6f17fe3941af2b8679a626f85d6012a284
diff --git a/.gitignore b/.gitignore
index 774a54c..95b37f0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -43,3 +43,6 @@
 
 # generated config
 genconfig/*
+
+# GitBook
+_book