Discourse allows to collaboratively work on articles.
For that we only have to click at the three dots at the bottom right of the message, find the gear and change the message into a wiki entry.
If we have done that for a message, we can notice the [Edit]-button below the message, which allows all to update its content now.
This message is the result of that.
If we want to turn it into a usual message again, we can do so as well.