How to make the action get just the last release and insert in changelog.md file?

I had a big old changelog.md.

recently I've migrated all realeases o Github. I've converted my old local changlog to your format and updated the chamglog.md file.
I need that on every nre relese the action insert just the last relase on top of the file, preserving my old history.

It's required because I cant recrate my local history in github, since I'm already usign Github releases