2.15: Fix typo under Replication plugin section

Change-Id: I8e80a6f2e7134bb3e17f252dc5a1143f480f7f66
diff --git a/pages/site/releases/2.15.md b/pages/site/releases/2.15.md
index 6db5c38..b9273de 100644
--- a/pages/site/releases/2.15.md
+++ b/pages/site/releases/2.15.md
@@ -365,7 +365,7 @@
 
 * It is now possible to replicate directly to another Gerrit instance.
 
-  Is is possible to enable replication to different Gerrit instance by using
+  It 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.