a civilized OpenZFS guide

This guide is intended to replace the various bits of ZFS documentation found online with something more comprehensive for OpenZFS. The closest thing I’ve been able to find for a comprehensive guide to ZFS is targeted specifically at Solaris ZFS, which always comes with caveats of not being quite accurate for OpenZFS.

My experience is definitely with ZFS on Linux, and that’s where the first draft of this guide will focus; but contributions specific to BSD, illumos, or other OpenZFS distributions are welcome and encouraged. (Where behavior or recommendations differ between platforms, these differences should be called out with no preference for any specific platform.)