Update 2.15 release notes

Change-Id: I16cb50da36c19cce3d53b7bd99bdff4a20296ba0
diff --git a/releases/2.15.md b/releases/2.15.md
index 9fe0ae6..4e4618c 100644
--- a/releases/2.15.md
+++ b/releases/2.15.md
@@ -313,6 +313,14 @@
   [symmetry](https://en.wikipedia.org/wiki/Equivalence_relation#Definition), so
   this behavior was removed: IdStrings now never compare equal to Strings.
 
+### Replication plugin
+
+* It is now possible to replicate directly to another Gerrit instance.
+
+  Is is possible to enable replication to different Gerrit instance by using
+  `gerrit+ssh://` as the protocol name followed by the hostname of another
+  Gerrit server.
+
 ## Dependency Updates
 
 * Update Apache Commons Codec to 1.10