key rotation usage guide text

Prior versions of KMIP support client-size key rotation methods.
This version of KMIP adds support for automatic rotation.
A client may now set the RotateAutomatic attribute to true to enable automatic rotation of keys by the server.
Additional attributes have also been added to enable more efficient handling and tracking of a series of keys that have been rotated via the RotateGeneration and RotateLatest attributes.

Tim.