[gentoo-project] Become a Developer has a broken link to Gentoo Developer Handbook

I just noticed that
<https://www.gentoo.org/get-involved/become-developer/> links to
<https://wwwold.gentoo.org/proj/en/devrel/handbook/handbook.xml> ("This
page serves as a brief overview of the process, if you want to learn
more, please see the Gentoo Developer Handbook which is currently still
only available as part of our old website.")

However, the link is broken.

I'm concerned this can be a really bad experience for someone who
considers becoming a Gentoo developer.

An easy fix is to remove the link, but there was also some content there
that may need to be migrated.

Can I somehow help with this?

Paweł