Update Pi-hole configuration to v6 (and provide notes for those upgrading)

[geerlingguy]

Pi-hole v6 is here: https://pi-hole.net/blog/2025/02/18/introducing-pi-hole-v6/

The environment variables for Docker are a bit different than previous versions—see https://docs.pi-hole.net/docker/

Hopefully it's a quick and easy shift to the new setup!

[bluttmer]

HI Jeff,

Will you need people to help test? I have a rpi 4b 8gig running ubuntu 24.04.

Ive had some issues getting to to work so not sure if that would be an issue.

Thank you again for all your great ideas and videos.

Bill