Get latest docs.

diff --git a/doc b/doc
index 34d0d136fba02910d9f3163f2a400ad4a8d9f148..e3c4e934a4b26051d524e25401d9e575d7a4c306 160000 (submodule)
--- a/doc
+++ b/doc
@@ -1 +1 @@
-Subproject commit 34d0d136fba02910d9f3163f2a400ad4a8d9f148
+Subproject commit e3c4e934a4b26051d524e25401d9e575d7a4c306