Enable Discussions for this repository

GitHub has introduced [Discussions](https://docs.github.com/en/discussions/collaborating-with-your-community-using-discussions/about-discussions) a while ago. In a nutshell, the idea is to use issues just for that and move general talk into discussions. Since there's no place to talk about all things Sirius/Little Printer, it would be lovely if the maintainers would enable it!