Ruby

fileutils.rb: improve rdoc for FileUtils

• lib/fileutils.rb: [DOC] fix invalid example code to make it
  syntax highlighted, fix rdoc for lists, nodoc internal methods,
  avoid a dangerous example.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57751 b2dd03c8-39d4-4d8f-98ff-823fe69b080e