docs(changelog) adds missing entry to changelog

CHANGELOG.md

@@ -7,17 +7,23 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+
 ### Changed
-- Adds a new method `try_seek` to all sources. It returns either an error or
-  seeks to the given position. A few sources are "unsupported" they return the
-  error `Unsupported`.
 - `Source` trait is now also implemented for `Box<dyn Source>` and `&mut Source`
 - `fn new_vorbis` is now also available when the `symphonia-vorbis` feature is enabled
 
 ### Added 
+- Adds a new method `try_seek` to all sources. It returns either an error or
+  seeks to the given position. A few sources are "unsupported" they return the
+  error `Unsupported`.
 - Adds `SpatialSink::clear()` bringing it in line with `Sink`
 
 ### Fixed
+- channel upscaling now follows the 'WAVEFORMATEXTENSIBLE' format and no longer
+  repeats the last source channel on all extra output channels. 
+  Stereo content playing on a 5.1 speaker set will now only use the front left
+  and front right speaker instead of repeating the right sample on all speakers
+  except the front left one.
 - `mp3::is_mp3()` no longer changes the position in the stream when the stream
   is mp3