Fix a couple of links in runtime/observatory

runtime/observatory/lib/src/elements/view_footer.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library view_footer_element;
 
 import 'dart:html';
 import 'dart:async';
 import 'package:observatory/src/elements/helpers/tag.dart';
 import 'package:observatory/src/elements/helpers/rendering_scheduler.dart';
@@ skipping 22 matching lines @@
   @override
   void detached() {
     super.detached();
     children = [];
     _r.disable(notify: true);
   }
 
   void render() {
     children = [
       new AnchorElement()
-        ..href = 'https://www.dartlang.org/tools/observatory'
+        ..href = 'https://dart-lang.github.io/observatory/'
         ..text = 'View documentation',
       new AnchorElement()
         ..href =
             'https://github.com/dart-lang/sdk/issues/new?title=Observatory:&body=Observatory%20Feedback'
         ..text = 'File a bug report'
     ];
   }
 }