docs: update the req.range jsdoc comment

lib/request.js

@@ -171,26 +171,26 @@ req.acceptsLanguage = deprecate.function(req.acceptsLanguages,
   'req.acceptsLanguage: Use acceptsLanguages instead');
 
 /**
- * Parse Range header field,
- * capping to the given `size`.
+ * Parse Range header field, capping to the given `size`.
  *
- * Unspecified ranges such as "0-" require
- * knowledge of your resource length. In
- * the case of a byte range this is of course
- * the total number of bytes. If the Range
- * header field is not given `null` is returned,
- * `-1` when unsatisfiable, `-2` when syntactically invalid.
+ * Unspecified ranges such as "0-" require knowledge of your resource length. In
+ * the case of a byte range this is of course the total number of bytes. If the
+ * Range header field is not given `undefined` is returned, `-1` when unsatisfiable,
+ * and `-2` when syntactically invalid.
  *
- * NOTE: remember that ranges are inclusive, so
- * for example "Range: users=0-3" should respond
- * with 4 users when available, not 3.
+ * When ranges are returned, the array has a "type" property which is the type of
+ * range that is required (most commonly, "bytes"). Each array element is an object
+ * with a "start" and "end" property for the portion of the range.
  *
- * @param {Number} size
- * @return {Array}
+ * NOTE: remember that ranges are inclusive, so for example "Range: users=0-3"
+ * should respond with 4 users when available, not 3.
+ *
+ * @param {number} size
+ * @return {number|array}
  * @public
  */
 
-req.range = function(size){
+req.range = function range(size) {
   var range = this.get('Range');
   if (!range) return;
   return parseRange(size, range);