2.14 release notes: include "Creating Changes for Merged Commits" feature

Appears to be introduced in 2.14 with change I4de55806cb, but not mentioned
in the release notes.

Change-Id: Ic05adefd97be85941ab31b4930a365fb8d035336
diff --git a/releases/2.14.md b/releases/2.14.md
index 9144703..dfeaf51 100644
--- a/releases/2.14.md
+++ b/releases/2.14.md
@@ -267,6 +267,13 @@
 * [Issue 4507](https://bugs.chromium.org/p/gerrit/issues/detail?id=4507):
 Add support for elliptic curve/ed25519 SSH keys.
 
+### Creating Changes for Merged Commits
+
+Normally, changes can be reviewed only before they are being merged. This new
+feature allows for post-submit review of commits by creating a new merged
+change, by using the
+['merged' push option](https://gerrit-documentation.storage.googleapis.com/Documentation/2.14/user-upload.html#merged).
+
 ## Bugfixes
 
 * [Issue 5234](https://bugs.chromium.org/p/gerrit/issues/detail?id=5234):