Lots of references to deprecated ways of doing things, as well as two
entire separate sections dedicated to how disk erasure works.
Also ensured we reference new valid config options surrounding disk
erasure.
Additional improvments could include adding documentation around how to
skip disks per node (or linking to any preexisting docs around it).
Change-Id: Ifa029e26eff0637b443d094d85e773b885d0979b
1aa780377e