Include changeset(s) verbatim in bot message?

[hmans]

This is a feature request (or maybe me trying to find out if this is even feasible to do; if it is, I might have a stab at making a PR): when the bot finds changesets in a PR, it will post a comment to the PR saying so. It would be great if this comment would also include the contents of the changesets. This would be a nice, frictionless way of surfacing the changes in the PR.