Update NetApp volume driver docs to add table on extra specs, leverage
updated config option docs, and general copy-editing.

Change-Id: I05cc3807ecc741c476ffd8883fe2aded95afe580
Partial-Bug: 1255215
Replaced 'EXISTING_STUFF_HERE' with '...'

Replaced 'EXISTING_STUFF_HERE' with '...' for consistency with
other parts of the documentation.

Change-Id: I0fb15fecdeeb689d03d1c91e52505cbc3dba023a
Closes-Bug: #1248669
Merge "Update NetApp volume driver docs to add table on extra specs, leverage updated config option docs, and general copy-editing."
Merge "Replaced 'EXISTING_STUFF_HERE' with '...'"