Reorganize docs into user/admin guide
Refresh the user and admin guide for v3 changes, and reorganize into
a narrative structure which makes more sense for v3.
Change-Id: I4ac3b18d5ed33b0fea4e2ef0318b19bfc3447ccc
diff --git a/doc/source/admin/drivers/zuul.rst b/doc/source/admin/drivers/zuul.rst
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+:title: Zuul Driver
+
+Zuul
+====
+
+The Zuul driver supports triggers only. It is used for triggering
+pipelines based on internal Zuul events.
+
+Trigger Configuration
+---------------------
+
+Zuul events don't require a special connection or driver. Instead they
+can simply be used by listing **zuul** as the trigger.
+
+**event**
+The event name. Currently supported:
+
+ *project-change-merged* when Zuul merges a change to a project,
+ it generates this event for every open change in the project.
+
+ *parent-change-enqueued* when Zuul enqueues a change into any
+ pipeline, it generates this event for every child of that
+ change.
+
+**pipeline**
+Only available for ``parent-change-enqueued`` events. This is the
+name of the pipeline in which the parent change was enqueued.
+
+*require-approval*
+This may be used for any event. It requires that a certain kind
+of approval be present for the current patchset of the change (the
+approval could be added by the event in question). It follows the
+same syntax as the :ref:`"approval" pipeline requirement
+<pipeline-require-approval>`. For each specified criteria there must
+exist a matching approval.
+
+*reject-approval*
+This takes a list of approvals in the same format as
+*require-approval* but will fail to enter the pipeline if there is
+a matching approval.