Docs: reformat zuul driver docs
Change-Id: Ieb973087acebb0eb34ee70c1f5ccdab59718ebfe
diff --git a/doc/source/admin/drivers/zuul.rst b/doc/source/admin/drivers/zuul.rst
index b531754..d95dffc 100644
--- a/doc/source/admin/drivers/zuul.rst
+++ b/doc/source/admin/drivers/zuul.rst
@@ -10,18 +10,29 @@
---------------------
Zuul events don't require a special connection or driver. Instead they
-can simply be used by listing **zuul** as the trigger.
+can simply be used by listing ``zuul`` as the trigger.
-**event**
- The event name. Currently supported:
+.. attr:: pipeline.trigger.zuul
- *project-change-merged* when Zuul merges a change to a project, it
- generates this event for every open change in the project.
+ The Zuul trigger supports the following attributes:
- *parent-change-enqueued* when Zuul enqueues a change into any
- pipeline, it generates this event for every child of that
- change.
+ .. attr:: event
+ :required:
-**pipeline**
- Only available for ``parent-change-enqueued`` events. This is the
- name of the pipeline in which the parent change was enqueued.
+ The event name. Currently supported events:
+
+ .. value:: project-change-merged
+
+ When Zuul merges a change to a project, it generates this
+ event for every open change in the project.
+
+ .. value:: parent-change-enqueued
+
+ When Zuul enqueues a change into any pipeline, it generates
+ this event for every child of that change.
+
+ .. attr:: pipeline
+
+ Only available for ``parent-change-enqueued`` events. This is
+ the name of the pipeline in which the parent change was
+ enqueued.