Terraform plan custom comment

[BostjanBozic]

Suggestion

I am not sure if this would be more of a niche thing - for me, it would be great if there would be an option to control the PR comment of terraform-plan action. Maybe not fully control, but just have an option to paste additional string.

My use-case is that once PR is merged, terraform-plan action will run only if PR includes specific label (this is to make sure people don't just merge PR without checking if something will be changed/deleted). It happened to me quite often that I forgot to add this label :) With this option, I would add it to terraform-plan comment itself as a reminder.

Great job otherwise with those actions, extremely useful :)