Fix link to CSI ephemeral volumes

Author: michielvangendt

content/en/docs/concepts/storage/ephemeral-volumes.md

@@ -46,7 +46,7 @@ different purposes:
   [downwardAPI](/docs/concepts/storage/volumes/#downwardapi),
   [secret](/docs/concepts/storage/volumes/#secret): inject different
   kinds of Kubernetes data into a Pod
-- [CSI ephemeral volumes](#csi-ephemeral-volume):
+- [CSI ephemeral volumes](#csi-ephemeral-volumes):
   similar to the previous volume kinds, but provided by special
   [CSI drivers](https://github.com/container-storage-interface/spec/blob/master/spec.md)
   which specifically [support this feature](https://kubernetes-csi.github.io/docs/drivers.html)