lib/rexml/document.rb, lib/rexml/element.rb,
lib/rexml/formatters/pretty.rb: remove opinionated
language in documentation. [Bug #8309],
reported by Charles Beckmann

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40420 b2dd03c8-39d4-4d8f-98ff-823fe69b080e