Update books

diff --git a/src/doc/book b/src/doc/book
index 98904efaa4fc968db8ff59cf2744d9f7ed158166..67b768c0b660a069a45f0e5d8ae2f679df1022ab 160000 (submodule)
--- a/src/doc/book
+++ b/src/doc/book
@@ -1 +1 @@
-Subproject commit 98904efaa4fc968db8ff59cf2744d9f7ed158166
+Subproject commit 67b768c0b660a069a45f0e5d8ae2f679df1022ab

diff --git a/src/doc/nomicon b/src/doc/nomicon
index 9493715a6280a1f74be759c7e1ef9999b5d13e6f..90993eeac93dbf9388992de92965f99cf6f29a03 160000 (submodule)
--- a/src/doc/nomicon
+++ b/src/doc/nomicon
@@ -1 +1 @@
-Subproject commit 9493715a6280a1f74be759c7e1ef9999b5d13e6f
+Subproject commit 90993eeac93dbf9388992de92965f99cf6f29a03

diff --git a/src/doc/reference b/src/doc/reference
index 411c2f0d5cebf48453ae2d136ad0c5e611d39aec..70fc73a6b908e08e66aa0306856c5211312f6c05 160000 (submodule)
--- a/src/doc/reference
+++ b/src/doc/reference
@@ -1 +1 @@
-Subproject commit 411c2f0d5cebf48453ae2d136ad0c5e611d39aec
+Subproject commit 70fc73a6b908e08e66aa0306856c5211312f6c05

diff --git a/src/doc/rustc-dev-guide b/src/doc/rustc-dev-guide
index 8763adb62c712df69b1d39ea3e692b6d696cc4d9..62f58394ba7b203f55ac35ddcc4c0b79578f5706 160000 (submodule)
--- a/src/doc/rustc-dev-guide
+++ b/src/doc/rustc-dev-guide
@@ -1 +1 @@
-Subproject commit 8763adb62c712df69b1d39ea3e692b6d696cc4d9
+Subproject commit 62f58394ba7b203f55ac35ddcc4c0b79578f5706