preserveUnknownField set to false, comments updates, adding pull request annotation
more comment updates
VolumeSnapshot comments
rename to VolumeSnapshotClassName
adding license
This PR adds new reserved prefixed parameter keys which are stripped
out of parameter list, and adds deprecation notice for old keys and
keep their behavior the same.
```
csiParameterPrefix = "csi.storage.k8s.io/"
prefixedSnapshotterSecretNameKey = csiParameterPrefix + "snapshotter-secret-name"
prefixedSnapshotterSecretNamespaceKey = csiParameterPrefix + "snapshotter-secret-namespace"
```