We are on 2016, and I would like to do the same thing, but "Comment" is not an option for Transition Actions anymore. (Why they would remove it is beyond me). I am trying to find a workaround.
So far I have tried choosing Set Variable as the Action. I set the Variable to itself and then set the Variable in the Comments box. The problem with this is that it bumps the Version of the file unnecessarily. I don't want to create version just to write a comment, and I should not have to.
The only other option that gives me a Version Comment box is to the Inc. Revision Action. This works but it does increment the Revision (in this case a minor revision) unnecessarily. To get around this I set the Revision increment to 0. This works, but for some reason it doesn't write the variable in the comments. Any other suggestions would be appreciated. I know in 2018 I could overwrite a version, but that is not an option at this time since we are on 2016.