What is signore?

I build my own version of the terraform-aws-provider and since a few release in the last steps the release script there is a need for a tool named signore.

What is signore ?

The only reference I could find is https://github.com/hashicorp/signore found in the README of GitHub - hashicorp/setup-signore and it leads to a 404.

Is this a private hashicorp tool ?