Corrections on the ZFS chapter:
- updates on sysctls for limiting IOPS during a scrub or resilver
- wording and grammar fixes
- comment out sections that will come in later once the chapter is officially available in the handbook

Submitted by:	Allan Jude
Fixes to grammar and language for the section on snapshots and clones
that I added a while back.

Submitted by:	bjk
Reducing the output of
igor -y chapter.xml
to only include those sentences where these fill-words actually make sense.

In addition to that, add acronym tags around another occurance of RAM.

With help from:	    Allan Jude
Editorial pass done.  Sections zfs-zfs-snapshot-creation through
zfs-zfs-clones need less confusing examples and rewrites to match.
zfs-send-ssh needs a clearer explanation of the -d option and
possibly examples.
Latest edits for clarity and consistency.
More assorted fixes and cleanups.