Update StorageClass API endpoint
Update StorageClass API endpoint

It has been moved from extensions/ to storage.k8s.io/ in 1.4.

rata/kubernetes.github.io,rata/kubernetes.github.io,aidevops/kubernetes.github.io,aidevops/kubernetes.github.io,rata/kubernetes.github.io,aidevops/kubernetes.github.io,rata/kubernetes.github.io,rata/kubernetes.github.io,erictune/erictune.github.io,erictune/erictune.github.io,erictune/erictune.github.io,aidevops/kubernetes.github.io,aidevops/kubernetes.github.io,erictune/erictune.github.io,erictune/erictune.github.io