Mention ref-update hook behavior change in 2.14 release notes

Change-Id: Iec4b4ec154744d6a24915b91b71477bef2969e91
diff --git a/releases/2.14.md b/releases/2.14.md
index e447670..9edf38a 100644
--- a/releases/2.14.md
+++ b/releases/2.14.md
@@ -65,6 +65,14 @@
 "Create Annotated Tag" and "Create Signed Tag". Existing project configurations
 using the old permission names will be migrated during site initialization.
 
+### Behavior change in ref-update hook
+
+Instead of being invoked on every commit received, the `ref-update` hook is now
+invoked before the ref update operation is finalized. The previous behavior of
+the `ref-update` hook is moved into a new hook named `commit-received`.
+
+Sites using the `ref-update` hook should rename the hook file to `commit-received`.
+
 ## New Features
 
 ### Change Assignee
@@ -191,6 +199,23 @@
 * [Issue 5234](https://bugs.chromium.org/p/gerrit/issues/detail?id=5234):
 Fix SSH GSSAPI authentication.
 
+* [Issue 5739](https://bugs.chromium.org/p/gerrit/issues/detail?id=5739):
+Prevent `ref-update` hook from being invoked on every commit when pushing
+multiple commits.
+
+    Instead of being invoked on every commit received, the `ref-update` hook
+    is now invoked before the ref update operation is finalized. Note that
+    the hook is no longer invoked on commits pushed for review or on changes
+    that are merged. It is invoked for creation/deletion of refs, and for
+    ref updates caused by direct pushes (i.e. bypassing review).
+
+    The previous behavior of the `ref-update` hook is moved into a new hook
+    named `commit-received`. A new parameter `--cmdref` is added, and the
+    special handling of `refs/for` and `refs/changes` is removed.
+
+    Sites using the `ref-update` hook should rename the hook file to
+    `commit-received`.
+
 ## Dependency Updates
 
 * Update auto-value to 1.4