The release blogs contain all fixes, so you can search for "Corona X released" and scan through it there. More tediously, you can go through the Daily Builds posts (there is only one Daily Build post for each version) and read all the daily builds released for a particular version (though the notes there contain regression fixes, e.g. fixing a bug that was introduced while writing that version, and that is cleaned up before the final blog post to detail only changes and fixes since the previous version).