It's great that there is a LICENSE file at the root of the project, but it doesn't reference the MIT license. This fixes that by copying verbatim the licensing line from backbone.js.
Adding the MIT license statement
Uh, the LICENSE file at the root of the project is the MIT license. It's the standard way to include it.
Right, but it doesn't say anywhere that it IS the MIT license. Unless you recognize the verbiage, it isn't obvious.
Some projects, like jQuery, indicate the license in the filename, like https://github.com/jquery/jquery/blob/master/MIT-LICENSE.txt. Others may indicate the type of license in the text.
Personally, I thin Remy Sharp's approach is pretty genius:
… but it might not be the right fit in this situation.