I think that the comments should be treated as a separate category of changes. That is, we have sections for Added, Removed, Moved, Changed. I would think it useful to have a Changed Comments. This is worthwhile because comment changes are much less important than code changes. If I do a lot of documentation changes, and in the same commit I happened to make a small code change (intentionally or not), I want that code change to stand out. The documentation is not nearly as important as the code itself.