docs: Argo Workflows and service account prereqs (#1391)

Signed-off-by: Jesse Antoszyk <[email protected]>

docs/sensors/triggers/argo-workflow.md

@@ -1,6 +1,6 @@
 # Argo Workflow Trigger
 
-Argo workflow is K8s custom resource which help orchestrating parallel jobs on Kubernetes. 
+Argo workflow is K8s custom resource which help orchestrating parallel jobs on Kubernetes.
 
 <br/>
 <br/>
@@ -13,11 +13,16 @@ Argo workflow is K8s custom resource which help orchestrating parallel jobs on K
 <br/>
 
 ## Trigger a workflow
+Note: You will need to have [Argo Workflows](https://argoproj.github.io/argo-workflows/) installed to make this work.
 
 1. Make sure to have the eventbus deployed in the namespace.
 
 1. We will use webhook event-source and sensor to trigger an Argo workflow.
 
+1. Set up the `operate-workflow-sa` service account that the sensor will use
+
+        kubectl apply -n argo-events -f https://raw.githubusercontent.com/argoproj/argo-events/master/examples/rbac/sensor-rbac.yaml
+
 1. Let's set up a webhook event-source to process incoming requests.
 
         kubectl apply -n argo-events -f https://raw.githubusercontent.com/argoproj/argo-events/stable/examples/event-sources/webhook.yaml