Consume events-broker from source

And mention this in the documentation.

Change-Id: Id891aa29d85ea6ba559dfea0ac0f9b7beb467e82

src/main/resources/Documentation/build.md

diff --git a/src/main/resources/Documentation/build.md b/src/main/resources/Documentation/build.md
index 38961f6..fe6b6de 100644
--- a/src/main/resources/Documentation/build.md
+++ b/src/main/resources/Documentation/build.md
@@ -6,10 +6,11 @@
 Clone (or link) this plugin to the `plugins` directory of Gerrit's source tree.
 
 Put the external dependency Bazel build file into the Gerrit /plugins directory,
-replacing the existing empty one.
-
+replacing the existing empty one. The rabbitMQ broker implementation depends on [events-broker](https://gerrit.googlesource.com/modules/events-broker)
+which is linked directly from source with the same 'in-tree' plugin structure.
 ```
   cd gerrit/plugins
+  git clone "https://gerrit.googlesource.com/modules/events-broker"
   rm external_plugin_deps.bzl
   ln -s @PLUGIN@/external_plugin_deps.bzl .
 ```