ANNOUNCE: ATF 0.21 released

[Julio Merino <jmmv%meroh.net@localhost>]

Hello everyone,

I'm pleased to announce that ATF 0.21 is available for download.

    https://github.com/jmmv/atf/releases/tag/atf-0.21

This is a major "cleanup release" in which many outstanding bugs have
been addressed and in which the documentation has significantly
improved to provide better usability.

Please refer to the link above for a link to the release file as well
as the detailed list of all changes.

Enjoy!