diff --git a/book b/book
index b8099b8..39e8013 160000
--- a/book
+++ b/book
@@ -1 +1 @@
-Subproject commit b8099b8b5021d212cd0c0a4c47fb6efac847c6b7
+Subproject commit 39e80131b3539cb9662a80b92065e424bc757e26