Add changelog to openapi page with versions list

[emilskra]

Openapi dashboard with the list of versions could display the summary of changes between versions in a hideable HTML element. This will make it easy to see the difference between versions for anyone within or outside the company (if necessary)

[emilskra]

Do after https://github.com/Ovsyanka83/universi/issues/43

[zmievsa]

This page would include all information from the version changes (yes, it means we'll need a way to render each type of version change).

[zmievsa]

This is now possible to easily integrate with verselect! Yaay!