Lemmy users probably shouldn't be able to make posts in the Ibis wiki communities

[K4LCIFER]

Ibis articles can be found in collections on Lemmy at !wiki@<ibis-instance-domain>; however, it seems that Lemmy users can post to these communities. This probably shouldn't be allowed. I feel like it would result in unexpected behavior.

[Nutomic]

Makes sense, but the question is how to implement it. Easiest option might be to set postingRestrictedToMods which is already supported by Lemmy. Then it would work as expected, but the definition doesnt quite match. The other option would be adding a new field, but that wouldnt be supported by older Lemmy versions or different platforms.