As a user I'd like to include all repos except an exclude list

[hughsaunders]

When setting up scheduled reminders, currently the options for including repos are all repos, or choose a list of repos.

If I choose all, then test repos will be included, potentially spamming the team. If I choose a list of repos to be included, then repos created in the future will not be included.

It would be useful to be able to include all repos except for a few that are specifically excluded.