For reference:
Node Author's email address: {{ node.uid.entity.mail.value }}
Node created: {{ node.created.value }}
Node Title: {{ node.title.value}}
Author's Username: {{ node.uid.entity.name.value }}
Node Edit Link: your website/node/{{ node.nid.value }}/edit
Example of my rule message body:
Hi {{ node.uid.entity.name.value }},
You created an event titled: {{ node.title.value}}
URL to edit your event: http://registration2.lndo.site/node/{{ node.nid.value }}/edit