Update README and fix broken links
I was updating a table for a project (EDITO WP5) and noticed that some links in the readme, like the one with docs for the gui, are broken (https://autosubmit.readthedocs.io/en/latest/autosubmit-gui.html).
I think it would be good to review the whole README and check for other broken links or things that could be improved (we've updated the AS readme some time ago, maybe we could use that as reference).