Update books

diff --git a/src/doc/book b/src/doc/book
index e5ed97128302d5fa45dbac0e64426bc7649a558c..cb28dee95e5e50b793e6ba9291c5d1568d3ad72e 160000 (submodule)
--- a/src/doc/book
+++ b/src/doc/book
@@ -1 +1 @@
-Subproject commit e5ed97128302d5fa45dbac0e64426bc7649a558c
+Subproject commit cb28dee95e5e50b793e6ba9291c5d1568d3ad72e

diff --git a/src/doc/nomicon b/src/doc/nomicon
index 25854752549d44d76fbd7650e17cb4f167a0b8fb..6e57e64501f61873ab80cb78a07180a22751a5d6 160000 (submodule)
--- a/src/doc/nomicon
+++ b/src/doc/nomicon
@@ -1 +1 @@
-Subproject commit 25854752549d44d76fbd7650e17cb4f167a0b8fb
+Subproject commit 6e57e64501f61873ab80cb78a07180a22751a5d6

diff --git a/src/doc/reference b/src/doc/reference
index 25391dba46262f882fa846beefaff54a966a8fa5..56a13c082ee90736c08d6abdcd90462517b703d3 160000 (submodule)
--- a/src/doc/reference
+++ b/src/doc/reference
@@ -1 +1 @@
-Subproject commit 25391dba46262f882fa846beefaff54a966a8fa5
+Subproject commit 56a13c082ee90736c08d6abdcd90462517b703d3