diff --git a/book b/book
index b763fe5..4981ad4 160000
--- a/book
+++ b/book
@@ -1 +1 @@
-Subproject commit b763fe56b0b324529b5cd85930d176742cbc800e
+Subproject commit 4981ad4b832d25317d6a91f10b9c04dc75322b9e