New review comment by ifreund on void-packages repository

https://github.com/void-linux/void-packages/pull/24580#discussion_r480227122

Comment:
not sure what the best option is here, and it may change as seatd matures. The `-g` flag sets the group which owns seatd's socket. The permissions of this socket determine which users are allowed access to seatd's capabilities. The `video` group is a reasonable default in my opinion, but we could also go with a seatd-specific group and ask people to add themselves to it in the install message.