docs($q): fix incorrect @returns tag for $q.when()

Author: frosas

src/ng/q.js

@@ -316,10 +316,7 @@ function qFactory(nextTick, exceptionHandler) {
    * the promise comes from a source that can't be trusted.
    *
    * @param {*} value Value or a promise
-   * @returns {Promise} Returns a single promise that will be resolved with an array of values,
-   *   each value corresponding to the promise at the same index in the `promises` array. If any of
-   *   the promises is resolved with a rejection, this resulting promise will be resolved with the
-   *   same rejection.
+   * @returns {Promise} Returns a promise of the passed value or promise
    */
   var when = function(value, callback, errback) {
     var result = defer(),