diff --git a/src/doc/book b/src/doc/book
index ec5660820dea9..98921e9de849a 160000
--- a/src/doc/book
+++ b/src/doc/book
@@ -1 +1 @@
-Subproject commit ec5660820dea91df470dab0b9eb26ef798f20889
+Subproject commit 98921e9de849acdaeaed08cfad6758bb89769b7d