+++ This bug was initially created as a clone of Bug #561770 +++ Section "Details" in https://www.gentoo.org/get-involved/become-developer/#details says: "[...] please see the Gentoo Developer Handbook which is currently still only available as part of our old website." and links to https://www.gentoo.org/proj/en/devrel/handbook/handbook.xml. The link is broken.
Link gone as noone seems to care about the handbook.