diff --git a/book b/book
index 9151969..57d0404 160000
--- a/book
+++ b/book
@@ -1 +1 @@
-Subproject commit 915196974ded5b6889e143ffccf513a9e8cdf33d
+Subproject commit 57d04049085ebab03e991384fd3fabec3fd821d8