Update storage-service.js

Clean up download API doc.

lib/storage-service.js

@@ -240,10 +240,10 @@ StorageService.prototype.upload = function(req, res, options, cb) {
 };
 
 /**
- * Download middleware <!-- Should this be documented? -->
+ * Download middleware 
  * @param {String} container Container name
  * @param {String} file File name
- * @param {Request} HTTP request
+ * @param {Request} req HTTP request
  * @param {Response} res HTTP response
  * @param {Function} cb Callback function
  */