Moving this here from the community google group:

Overview of the Feature Request
While the version table includes a list/diff of changes, there is no way to specify the occasion/reason for a version change (new data? major error in the data? small typo? format update for preservation?, etc.). Including this as a metadata field would be very helpful. As per @jggautier, this exists in both DataCite and DDI metadata and actually used to exist in metadata:

DDI Codebook has an element called verStmt that the Dataverse software mapped to its versioning notes field. I looked around but couldn't find any discussion from back then about why that field was removed. Maybe Sonia or the folks from Odum might know why. (...)

The DataCite schema has a way to include a description of version changes, too, if the software were to add a field for that and wanted to include version notes in that export.

What kind of user is the feature intended for?

• Depositors, Curators, and data users

What inspired the request?

• We're increasingly updating data for a variety of reasons and it'd be helpful to make it clear why, since some updates do make meaningful changes, others just affect preservation or accessibility and it'd be good for users to be clear on this, e.g. when datasets serve as a version of record of sorts for preservation.
• Odum via @donsizemore & @jonc1438 also said they're interested

What existing behavior do you want changed?
I see three implementation options -- we'd be happy with any of them, but others may have preferences:

1. The field could just be a regular metadata field. Easiest implementation, but potentially a cause for bad data entry, especially on self deposits
2. The field could be a regular metadata field but only show after v1 is published
3. The field could be an active prompt on version changes

The main difference between 2 and 3 would likely be that 3 would make it more likely that self deposits with version updates include these changes.

Any brand new behavior do you want to add to Dataverse?
No

Any related open or closed issues to this feature request?
There are several open issues related to versioning (#4499 is probably most relevant ), but none directly addressing this that I could find.