Mention circle in markdown documents

[PatrickJosh]

Is your feature request related to a problem? Please describe.
I use Nextcloud in an association and we had the idea to use circles to organise who has which roles. It would be really nice if we could mention the circles in a markdown document as you can with single people, e.g. it is relevant for the whole circle/role or if someone in the circle should do something, but it is irrelevant who exactly does it.

Describe the solution you'd like
You can just mention circles as any singular person. Everyone in this circle receives a notification.

Describe alternatives you've considered
If it is easier to implement it with groups, this might also be a first idea. But since groups are only manageable by (group) admins, I think it should be possible to mention circles in the end as well.

Additional context
Maybe there should be a setting that disables this feature so that not everyone can mention a lot of people simultaneously.

[juliushaertl]

I think we should cover both groups and circles here 👍