fix a few grammar things, and deprecate 'servers' and 'nodes'

also clarify a few explanations. so far so good!
use the formatting from 0.2.4.21 for the 0.2.4.21 changelog stanza
missing colon
sort stanzas by interest, and sort by version within stanzas

(users want to know about client fixes before they want to know about
unit test fixes.)