Be cautious with this - collaboration is more tricky than it seems.
A few months back I've been searching for Markdown collaboration tools for my team and all of the tools that promise that have some sersious issues. Ie. loosing comments, loosing content, not refreshing the content, versioning, etc.
I don't perceive Bear to be this kind of app for collaboration. It seems to be focused on individual workflow and that's what seesm sto work great. On top of that Bear is Apple centered and people from other platforms couldn't collaborate.
Btw. I'm still searching for a good tool for team collaboration on .MD. If somebody knows about such a tool, I'd love to hear about it :) In the mean time we've settled on the least-broken Classeur.