Fix docker stack link

Signed-off-by: Wen Cheng Ma <wenchma@cn.ibm.com>

experimental/README.md

@@ -73,7 +73,7 @@ to build a Docker binary with the experimental features enabled:
 
  * [External graphdriver plugins](plugins_graphdriver.md)
  * [Macvlan and Ipvlan Network Drivers](vlan-networks.md)
- * [Docker stacks](docker-stacks.md)
+ * [Docker Stacks and Distributed Application Bundles](docker-stacks-and-bundles.md)
 
 ## How to comment on an experimental feature