Add required Gerrit version in README
diff --git a/README.md b/README.md
index e0728ef..77d6397 100644
--- a/README.md
+++ b/README.md
@@ -14,6 +14,7 @@
 This can publish gerrit events to message queue provided by RabbitMQ.
 Published events are the same as Gerrit stream evnets.
 
+This plugin works on Gerrit 2.8 or later.
 
 Build
 ---------------------