Hey everyone,
I have created an example plugin to override default Activity Summary (digest) template:
https://github.com/muhlisbc/discourse-custom-activity-summary-template
Screenshot:
https://github.com/muhlisbc/discourse-custom-activity-summary-template/raw/master/custom-digest1.jpg
https://github.com/muhlisbc/discourse-custom-activity-summary-template/raw/master/custom-digest2.jpg
The main purpose of this plugin is to show how to override default .erb templates on Discourse.
I hope this helpful for someone.