Update books for next release

diff --git a/src/doc/book b/src/doc/book
index 36d65d00164d1750f6fa7f8b0f52dabc3fea500b..f475da63a18d50217459a601cbef69a4bcac5e71 160000 (submodule)
--- a/src/doc/book
+++ b/src/doc/book
@@ -1 +1 @@
-Subproject commit 36d65d00164d1750f6fa7f8b0f52dabc3fea500b
+Subproject commit f475da63a18d50217459a601cbef69a4bcac5e71

diff --git a/src/doc/nomicon b/src/doc/nomicon
index 748a5e6742db4a21c4c630a58087f818828e8a0a..13e3745ca399118df05e8261e12e3ada6e616b48 160000 (submodule)
--- a/src/doc/nomicon
+++ b/src/doc/nomicon
@@ -1 +1 @@
-Subproject commit 748a5e6742db4a21c4c630a58087f818828e8a0a
+Subproject commit 13e3745ca399118df05e8261e12e3ada6e616b48

diff --git a/src/doc/reference b/src/doc/reference
index 134f419ee62714590b04712fe6072253bc2a7822..0f63519ea10c028f48b2dbf7d0a2454203b68b0b 160000 (submodule)
--- a/src/doc/reference
+++ b/src/doc/reference
@@ -1 +1 @@
-Subproject commit 134f419ee62714590b04712fe6072253bc2a7822
+Subproject commit 0f63519ea10c028f48b2dbf7d0a2454203b68b0b

diff --git a/src/doc/rust-by-example b/src/doc/rust-by-example
index eebda16e4b45f2eed4310cf7b9872cc752278163..d2a64395a5210a61d3512a3a5c615f5c47699443 160000 (submodule)
--- a/src/doc/rust-by-example
+++ b/src/doc/rust-by-example
@@ -1 +1 @@
-Subproject commit eebda16e4b45f2eed4310cf7b9872cc752278163
+Subproject commit d2a64395a5210a61d3512a3a5c615f5c47699443