There are changelogs in itch, although they're not really integrated with the app.
You can see on https://fasterthanlime.itch.io/thorny-weather for example, there's a "Developer Log" section.
After pushing a build, if you visit your page while logged in (so, from the app for example), you'll have the option to write a dev log for the latest version. You'll also have that in the "Edit game page", in the "Devlog" section.
Where you asking whether there's a way to push them programmatically with butler?