Consider this the initial release. The previous alpha versions were designed completely different, so release notes don't apply for this release. We will maintain a CHANGELOG from now on: https://github.com/elixir-lang/elixir/blob/master/CHANGELOG....

Although it doesn't have a complete list of changes you can check some changes in the blog.

http://elixir-lang.org/blog/

There are some posts with a little summary of what happened during the week.