More rust docs

Switch from allow(missing_docs) to deny(missing_docs), which should
gradually help us moving forward.  Also, add a few missing docs, such as
for sched and aio.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/env.rs b/src/env.rs
index 613b0cd8..54d75959 100644
--- a/src/env.rs
+++ b/src/env.rs
@@ -1,3 +1,4 @@
+//! Environment variables
 use cfg_if::cfg_if;
 use std::fmt;