If my code is lib/Book/Page.pm, should it be lib/Book/Page.pod

That appears to be where perldoc looks for it. So IMO all you have to do is mention it in you module's MANIFEST, and it should then be included in your distro and installed with make.

But, that's what I expect, it's an untested claim. Why don't you test it? You have all the files handy. Add it the file to MANIFEST, do make tardist, and then extract the archive to a new location, do both perl Makefile.PL and make, and see that the POD gets where it should be. Right next to the .pm file.