Many of the filesystems in FreeBSD have a section 5 manpage for them (see msdosfs(5), tmpfs(5), etc), which describes what kernel options are required in order to load the filesystem, how it can be managed (via fstab(5), mount(8), etc). zfs(5) doesn't exist though.
Adding Sean to cc as he has some ideas for zfs(5).
Diff available for review here:
After commentary, I will attach the final version.