Section 8c of the Gentoo Handbook lists that the user should configure /etc/rc.conf. This file was split into /etc/rc.conf and /etc/conf.d/rc, but no mention of it is made in the handbook. As this contains multiple configuration variables and is well commented, it may be considered a good addition to the handbook. Reproducible: Always
That's because there's nothing in conf.d/rc that really needs to be edited at this point in the install process. Necessary edits are covered in the networking and other sections of the handbook. Nothing to add here as far as I'm concerned.