Add documentation about rootless use

[eriksjolund]

I searched for "rootless" in the documentation but didn't find anything:
https://docs.linuxserver.io/?q=rootless

I see that using rootless Podman or rootless Docker is not supported.

containers/podman#15313 (comment)

containers/podman#15313 (comment)

Could you add a note to documentation (https://docs.linuxserver.io)
that using rootless Podman and rootless Docker is not supported?

[sammcj]

Came wondering the same thing!

[raycadle]

I'm using rootless podman to run a few LSIO containers (specifically Nextcloud, Mariadb, and Syncthing) and I've had no container related issues so far. I would be happy to contribute that bit of documentation if it would be of use to the community.

[raycadle]

Created a PR #129, adding documentation around using rootless podman containers.

[thespad]

This is now covered in our Support Policy.

Most of our images will work in a rootless environment if you understand what you're doing, some just aren't going to and there's nothing we can practically do to make them work. We don't formally support rootless operation but we'll make reasonable efforts to help with issues people encounter and provide fixes where they don't impact rootful users.