1.3.1: changelog summary & release date

Author: sampsyo

docs/changelog.rst

@@ -1,10 +1,16 @@
 Changelog
 =========
 
-1.3.1 (in development)
-----------------------
+1.3.1 (October 12, 2013)
+------------------------
+
+This release boasts a host new little features, many of them contributed by
+beets' amazing and prolific community. It adds support for `Opus`_ files,
+transcoding to any format, and two new plugins: one that guesses metadata for
+"blank" files based on their filenames and one that moves featured artists
+into the title field.
 
-New stuff:
+Here's the new stuff:
 
 * Add `Opus`_ audio support. Thanks to Rowan Lewis.
 * :doc:`/plugins/convert`: You can now transcode files to any audio format,