This is relevant when docker is used as container runtime as it does not
set /tmp as tmpfs. With podman /tmp is mounted as tmpfs due to
`--read-only-tmpfs` (enabled by default).
Fixes: #3463
Move the container image and binary download details from the README
into a dedicated documentation page at setup/install/main. This gives
development builds a proper home in the docs site alongside the other
install methods. The README now links to the docs page instead.
Florian Preinstorfer
Kristoffer Dalby