Updating forkJoin docs

Author: mattpodwysocki

dist/rx.all.compat.js

@@ -1,37 +1,58 @@
-### `Rx.Observable.forkJoin(...args)`
+### `Rx.Observable.forkJoin(...args, [resultSelector])`
 [Ⓢ](https://github.com/Reactive-Extensions/RxJS/blob/master/tests/observable/forkjoin.js "View in source")
 
 Runs all observable sequences in parallel and collect their last elements.
 
 #### Arguments
 1. `args` *(Arguments | Array)*: An array or arguments of Observable sequences or Promises to collect the last elements for.
+2. `resultSelector`: `Function` - The result selector from all the values produced. If not specified, `forkJoin` will return the results as an array.
 
 #### Returns
-*(`Observable`)*: An observable sequence with an array collecting the last elements of all the input sequences.
+*(`Observable`)*: An observable sequence with an array collecting the last elements of all the input sequences or the result of the result selector if specified.
 
 #### Example
 ```js
-/* Using observables and Promises */
+/* Without a selector */
 var source = Rx.Observable.forkJoin(
-    Rx.Observable.return(42),
-    Rx.Observable.range(0, 10),
-    Rx.Observable.from([1,2,3]),
-    RSVP.Promise.resolve(56)
+  Rx.Observable.return(42),
+  Rx.Observable.range(0, 10),
+  Rx.Observable.from([1,2,3]),
+  RSVP.Promise.resolve(56)
 );
 
 var subscription = source.subscribe(
-    function (x) {
-        console.log('Next: ' + x);
-    },
-    function (err) {
-        console.log('Error: ' + err);
-    },
-    function () {
-        console.log('Completed');
-    });
+  function (x) {
+    console.log('Next: %s', x);
+  },
+  function (err) {
+    console.log('Error: %s', err);
+  },
+  function () {
+    console.log('Completed');
+  });
 
 // => Next: [42, 9, 3, 56]
 // => Completed
+
+var source = Rx.Observable.forkJoin(
+  Rx.Observable.just(42),
+  Rx.Observable.just(56),
+  function (x, y) { return x + y; }
+);
+
+var subscription = source.subscribe(
+  function (x) {
+    console.log('Next: %s', x);
+  },
+  function (err) {
+    console.log('Error: %s', err);
+  },
+  function () {
+    console.log('Completed');
+  });
+
+// => Next: 98
+// => Completed
 ```
 
 ### Location