conversions were done using https://github.com/pennae/nix-doc-munge
using (probably) rev f34e145 running
nix-doc-munge nixos/**/*.nix
nix-doc-munge --import nixos/**/*.nix
the tool ensures that only changes that could affect the generated
manual *but don't* are committed, other changes require manual review
and are discarded.
The `iotop` program can't be started by an unprivileged user because of
missing root privileges. The issue can be fixed by creating a
setcap wrapper for `iotop` which contains `cap_net_admin`.