`"default"` is an exception -- [it's a reserved word in JavaScript](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Reserved_Words), and some JavaScript preprocessors (like YUI compiler) explode if they encounter an unquoted reserved word as an object key. 

Since this is just documentation, it's no big deal but in the codebase we're going to keep `"default"` quoted.