Dicussions are open now

[WolfgangFahl]

Thanks for closing #1627.
There are a few issues labeled as https://github.com/jupyter/nbgrader/labels/discussion that could be moved here now by applying the
"Converting issues to discussion" procedure as outlined in https://docs.github.com/en/discussions/managing-discussions-for-your-community/moderating-discussions.

[jhamrick]

Thanks, I've converted the existing discussion issues to discussions.