docs: Remove old reference to ovs-containers repo
docs: Remove old reference to ovs-containers repo

It's been replaced by ovs/Dockerfile.

secant/quilt,LuiseV/quilt,akshayknarayan/quilt,kklin/kelda,PenguinToast/quilt,NetSys/quilt,quilt/quilt,secant/quilt,stevenlin598/quilt,ZhongtianWang/quilt,stevenlin598/quilt,LuiseV/quilt,kelda/kelda,kayousterhout/quilt,LuiseV/quilt,kklin/quilt,mmussomele/quilt,ejj/quilt-dev,ZhongtianWang/quilt,PenguinToast/quilt,ejj/quilt-dev,mmussomele/quilt,PenguinToast/quilt,kelda/kelda,tejasmanohar/quilt,NetSys/quilt,mmussomele/quilt,kklin/quilt,kelda/kelda,PenguinToast/quilt,tejasmanohar/quilt,kayousterhout/quilt,akshayknarayan/quilt,stevenlin598/quilt,stevenlin598/quilt,kklin/kelda,akshayknarayan/quilt,ZhongtianWang/quilt,mmussomele/quilt,NetSys/quilt,PenguinToast/quilt,kayousterhout/quilt,tejasmanohar/quilt,ejj/quilt-dev,quilt/quilt,stevenlin598/quilt,kklin/quilt,kklin/quilt,secant/quilt,secant/quilt,kklin/kelda,kayousterhout/quilt,ejj/quilt-dev,mmussomele/quilt,kklin/kelda,ZhongtianWang/quilt,NetSys/quilt,LuiseV/quilt,NetSys/quilt,quilt/quilt,kelda/kelda,akshayknarayan/quilt,mmussomele/quilt,tejasmanohar/quilt,stevenlin598/quilt,quilt/quilt,secant/quilt,LuiseV/quilt