* update readme

* update and move old IO documentation to legacy page

* add documentation for IOSvc

* add comment on IOSvc default name

* fix link, fix missing determiners, remove paragraph of algortihms/service coupled with legacy io

Co-authored-by: jmcarcell <jmcarcell@users.noreply.github.com>

* Update README.md

Co-authored-by: Thomas Madlener <thomas.madlener@desy.de>

---------

Co-authored-by: jmcarcell <jmcarcell@users.noreply.github.com>
Co-authored-by: Thomas Madlener <thomas.madlener@desy.de>