Add CHANGELOG entry for shared packs
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 46b0759..4ae6462 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,3 +3,5 @@ v0.21 + 1
* File unlocks are atomic again via rename. Read-only files on Windows are
made read-write if necessary.
+
+* Share open packfiles across repositories to share descriptors and mmaps.