Update a comment for Toom3.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42084 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* doc/regexp.rdoc: [DOC] Fix typo in example [Fixes GH-365]
  Patch by Juanito Fatas https://github.com/ruby/ruby/pull/365


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42085 b2dd03c8-39d4-4d8f-98ff-823fe69b080e