docs: typo eventbus (argoproj#1486)

docs/eventbus.md

@@ -16,7 +16,7 @@ EventSource and Sensor work.
 
 The common practice is to create an EventBus named `default` in the namespace. If
 you want to use a different name, or you want to have multiple EventBus in one
-namespace, you need to specifiy `eventBusName` in the spec of EventSource and
+namespace, you need to specify `eventBusName` in the spec of EventSource and
 Sensor correspondingly, so that they can find the right one. See EventSource
 [spec](https://github.com/argoproj/argo-events/tree/stable/api/event-source.md#eventsourcespec)
 and Sensor