This PR *breaks* my code. If this were to be merged, I'd have to go through all my `cs_*` resources and add a `notify => Cs_shadow...` to preserve the behavior I have now. That kind of change deserves, at least, some prominent documentation. The [existing documentation](https://github.com/puppetlabs/puppetlabs-corosync/commit/1888e9305c4fe262f78d1c22ffd9a7e3348e08bc) doesn't say anything about notifying `cs_shadow` because it isn't necessary. The existing documentation has all the information needed to use the functionality; even if it is scant and hard to find, it's not incomplete.