Backport README change to .ja.md [ci skip]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@67682 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Backport README change to .ja.md [ci skip]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@67682 b2dd03c8-39d4-4d8f-98ff-823fe69b080e