Version comment cannot be updated

[Rastikko]

Seems like update showed version doesn't update the version comment

The only way to create or modify a version comment is by creating a new version.

Seems like this is done because we filter some attributes from the updateVersion PUT method: server/controllers/admin.js

Any reason we wouldn't allow to update the version comment? Seems like an important feature considering many times content creators might forget to add a comment on the first pass.