Specify compose stack name/directory in notification template

[skakdollar]

Is your feature request related to a problem? Please describe.

I update containers manually, and it would be nice to know the compose stack of a particular container to be updated in the update message.

Describe the solution you'd like

Please allow to specify the required variable in the template.

Describe alternatives you've considered

Did not see this anywhere else.

Additional context

No response

[github-actions]

Hi there! 👋🏼 As you're new to this repo, we'd like to suggest that you read our code of conduct as well as our contribution guidelines. Thanks a bunch for opening your first issue! 🙏