Adding Rohit Jnagal and Victor Marmol to pkg/cgroups maintainers.

Docker-DCO-1.1-Signed-off-by: Victor Marmol <vmarmol@google.com> (github: vmarmol)
Merge pull request #5535 from vmarmol/add-maintainers-cgroup

Adding Rohit Jnagal and Victor Marmol to pkg/cgroups maintainers.