Could someone tell me where I could find detailed information about what has beend changed/improved in a new WordPress major/minor version? Maybe some kind of changelog or something?
2 Answers
First of all you can follow WordPress Blog and its Releases category.
Another great source of information on that is page with WordPress Versions on Codex - here you can find info on every version - link to changelog (very useful - it contains list of changed files and links to trac tickets solved in this version) and to release article for that version on blog (mentioned in previous paragraph).
For example article for 5.0.3 version: https://wordpress.org/support/wordpress-version/version-5-0-3/
You can view WordPress releases at the codex. Check this out.
You can view the Roadmap here.