Slightly fix rdoc of with_index.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@22170 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Slightly fix rdoc of with_index.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@22170 b2dd03c8-39d4-4d8f-98ff-823fe69b080e