As a part of branching for 4.11 for Red Hat CoreOS, a `rhcos-4.10` branch was cut for fedora-coreos-config. Update .gitmodules to point to the `rhcos-4.10` branch of fedora-coreos-config.
This is a no-op for 4.11; will create a clone for 4.10.z
Close as CURRENTRELEASE based on Comment #1