It would be very helpful if a bot could use some markdown for message formatting. Any message templates available?
AFAIK, our Chat system (and thus the bots) do not support Markdown.
This feature request has been submitted to the engineering team and is on their backlog.
This is a good way to start with more complex messages, even without markdown:
Thanks, I will share this with our leads for Chat. 
Chatbots now support Markdown and @mentions!
GREAT! Will users be able to do the same soon?
Yes - but I don’t have an exact timeline on that.