v0.13.0-rc

• Enriched structure for events generated by the gateways #493. Refer https://github.com/argoproj/argo-events/blob/master/pkg/apis/events/event-data.go
• Introducing the custom triggers (Beta) #493
• Added support for generic event source #467
• Introducing gateway setup guides #507
• Fix filters for the resource gateway #499
• Fix Kafka gateway issue #490