Handbook/Storage: Various improvements
- Minor grammar updates
- Add tip about replicating using ZFS snapshots
- List popular backup utilities
- When backing up, keep a list prime packages
- Update sample CARP configuration
- Add tip about sharing highly available storage across the network
Reviewed by: emaste, jrm, Pau Amma <pauamma@gundo.com>
Differential Revision: https://reviews.freebsd.org/D43948