Should we put a LICENSE file in the Rails top level project directory?

Should we put a LICENSE file in the Rails top level project directory
to
define our license. It seems to be done in some open source projects.

Found these references:
http://dev.rubyonrails.org/browser/trunk/railties/MIT-LICENSE (this
link in broken)
http://weblog.rubyonrails.org/2006/1/24/pick-a-license-for-your-rails-additions
https://github.com/svenfuchs/rails-i18n/blob/master/MIT-LICENSE.txt
(example)
http://www.opensource.org/licenses/mit-license.php

Each component of Rails has its own copy of license file since they are packaged separately.
https://github.com/rails/rails/blob/master/railties/MIT-LICENSE

Yes, I found it later in the day. Sorry I did not look earlier.
Thanks.