Update doc about migration from apiserver to crd
Update doc about migration from apiserver to crd

kubernetes-sigs/service-catalog,kubernetes-incubator/service-catalog,kubernetes-sigs/service-catalog,kubernetes-sigs/service-catalog,kubernetes-sigs/service-catalog,kubernetes-sigs/service-catalog,kubernetes-sigs/service-catalog,kubernetes-incubator/service-catalog,kubernetes-incubator/service-catalog,kubernetes-incubator/service-catalog,kubernetes-incubator/service-catalog,kubernetes-incubator/service-catalog