* lib/set.rb: [DOC] Add examples for Set#intersect? and Set#disjoint?
  Patch by xavier nayrac [Bug #9331] [ci skip]


git-svn-id: svn+ssh://svn.ruby-lang.org/ruby/trunk@44724 b2dd03c8-39d4-4d8f-98ff-823fe69b080e