docs on stream are now outer attribute (fixes missing docs lint)

Author: dvdsk

src/stream.rs

@@ -1,3 +1,10 @@
+//! Output audio via the OS via mixers or play directly
+//!
+//! This module provides a builder that's used to configure and open audio output. Once
+//! opened sources can be mixed into the output via `OutputStream::mixer`.
+//!
+//! There is also a convenience function `play` for using that output mixer to
+//! play a single sound.
 use crate::common::{ChannelCount, SampleRate};
 use crate::decoder;
 use crate::mixer::{mixer, Mixer, MixerSource};