Reverse starting order on document diff

Problem

When comparing versions, the left document will be the last version, and the right one will be the second last.
This is not intuitive and usually, the user will want to check the differences from a later version to a newer one.

Proposed solution
Change the initial shown documents so that:

• left document is the second top document on the list
• right document is the top document on the list
  (basically, the reverse)