Docs repo Eventing updates for v0.5

[samodell]

/docs/docs/eventing

• README.md
• Images: add new broker trigger diagram

/docs/docs/eventing/debugging

• README.md
• example-model.png

[samodell]

Closed by #1125

/close

[knative-prow-robot]

@samodell: Closing this issue.

In response to this:

Closed by #1125

/close

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