As a general rule, we do not want to expose the cib to the user. There's some pretty explicit discussion of this in BZ#1085100.
We do, however, document the pcs cluster cib command to show how to make changes to a file locally and then push them to the whole cluster.
But the reason for this feature is not along those lines -- it's about removing resources and then adding them again. The use case of wanting to work locally on only a particular scope of cib and then pushing only that scope of changes back seems very narrow -- and can be addressed in the documentation on the help screen alone.
So after discussion with Chris Feist, I am closing this as not a bug. As noted, the feature remains documented on the help screen (which is pretty much all that would be in the manual anyway).