Any router guide that does not cover IPv6 is sadly obsolete.
Additionally, with a "home/office" router, there's many ways that IPv6 may be implemented by their ISP (e.g. static configured prefix, DHCPv6, prefix delegation etc...) all which require specific configuration on the WAN and LAN side to make it work.
So, I agree, but splitting that particular part into a different FAQ/walkthrough is going to be a better approach.
Comcast gets a lot of heat, but they at least have done ipv6 right.