Add instructions for RabbitMQBroker Api and custom gerrit event types

Change-Id: I6788bba8ba55767e8c8543b169d75fa782fed17f
diff --git a/src/main/resources/Documentation/build.md b/src/main/resources/Documentation/build.md
index fe6b6de..1153194 100644
--- a/src/main/resources/Documentation/build.md
+++ b/src/main/resources/Documentation/build.md
@@ -36,3 +36,15 @@
 ```
   ./tools/eclipse/project.py
 ```
+
+Use RabbitMQBroker Api with multi-site or another setup with custom Gerrit events
+------------------------------------------------------------------------------------
+
+To make events-rabbitmq able to deserialize events from the rabbitMQ queues, every event type needs
+to be registered before. This means that every plugin that needs to register its own event types
+needs to load before events-rabbimq. Gerrit load plugins lexicographically based on the names of
+the jars of the plugins. So in the case of multi-site you could rename replication.jar to
+0-replication.jar. Do not forget to re-point any symlinks.
+```
+  mv gerrit/plugins/replication.jar gerrit/plugins/0-replication.jar
+```