Changelog: add empty line after version lines

Fix spacing inconsistency.

Changelog

@@ -2,6 +2,7 @@ Entries are sorted chronologically from oldest to youngest within each release,
 releases are sorted from youngest to oldest.
 
 version next:
+
 - stream disposition information printing in ffprobe
 - filter for loudness analysis following EBU R128
 - Opus encoder using libopus
@@ -9,6 +10,7 @@ version next:
 
 
 version 1.0:
+
 - INI and flat output in ffprobe
 - Scene detection in libavfilter
 - Indeo Audio decoder