Build events-log for Gerrit 2.15

Change-Id: I8da43f38f1a2c3d06043c91fd15f6f2c1b8009c6
diff --git a/jenkins/gerrit-buck-bazel-plugin-events-log.yaml b/jenkins/gerrit-buck-bazel-plugin-events-log.yaml
index 0c9e832..2a95828 100644
--- a/jenkins/gerrit-buck-bazel-plugin-events-log.yaml
+++ b/jenkins/gerrit-buck-bazel-plugin-events-log.yaml
@@ -9,4 +9,5 @@
       - 'plugin-{name}-bazel-{branch}':
           branch:
             - master
+            - stable-2.15
             - stable-2.14