To trigger Notification to Community Members on adding new Learning Item in catalog inside Community

Summary:

Alerts to all community members whenever a new content is added to or deleted from community

Content (required):

A notification should be triggered to community members when a new course or any content is added to a Category community, topic community or official community.

This will help community members notify on new contents added and can go through the community and look into the content and complete it.

When we look into custom resource alert but not sure on Alert expression, how to get the criteria for this addition of new content in community. 

Can anyone please let us know, any alerts has been developed and worked for this scenario.