add `docker stack ls`

Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>

docs/reference/commandline/stack_config.md

@@ -29,3 +29,4 @@ Displays the configuration of a stack.
 * [stack rm](stack_rm.md)
 * [stack services](stack_services.md)
 * [stack tasks](stack_tasks.md)
+* [stack ls](stack_ls.md)

docs/reference/commandline/stack_deploy.md

@@ -58,3 +58,4 @@ axqh55ipl40h  vossibility-stack_vossibility-collector  1 icecrime/vossibility-co
 * [stack rm](stack_rm.md)
 * [stack services](stack_services.md)
 * [stack tasks](stack_tasks.md)
+* [stack ls](stack_ls.md)

docs/reference/commandline/stack_ls.md

@@ -0,0 +1,37 @@
+<!--[metadata]>
++++
+title = "stack ls"
+description = "The stack ls command description and usage"
+keywords = ["stack, ls"]
+advisory = "experimental"
+[menu.main]
+parent = "smn_cli"
++++
+<![end-metadata]-->
+
+# stack ls (experimental)
+
+```markdown
+Usage:	docker stack ls
+
+List stacks
+```
+
+Lists the stacks.
+
+For example, the following command shows all stacks and some additional information:
+
+```bash
+$ docker stack ls
+
+ID                 SERVICES
+vossibility-stack  6
+myapp              2
+```
+
+## Related information
+
+* [stack config](stack_config.md)
+* [stack deploy](stack_deploy.md)
+* [stack rm](stack_rm.md)
+* [stack tasks](stack_tasks.md)

docs/reference/commandline/stack_rm.md

@@ -32,3 +32,4 @@ a manager node.
 * [stack deploy](stack_deploy.md)
 * [stack services](stack_services.md)
 * [stack tasks](stack_tasks.md)
+* [stack ls](stack_ls.md)

docs/reference/commandline/stack_services.md

@@ -63,3 +63,4 @@ The currently supported filters are:
 * [stack deploy](stack_deploy.md)
 * [stack rm](stack_rm.md)
 * [stack tasks](stack_tasks.md)
+* [stack ls](stack_ls.md)

docs/reference/commandline/stack_tasks.md

@@ -45,3 +45,4 @@ The currently supported filters are:
 * [stack deploy](stack_deploy.md)
 * [stack rm](stack_rm.md)
 * [stack services](stack_services.md)
+* [stack ls](stack_ls.md)

experimental/docker-stacks-and-bundles.md

@@ -93,6 +93,7 @@ Options:
 Commands:
   config      Print the stack configuration
   deploy      Create and update a stack
+  ls          List stacks
   rm          Remove the stack
   services    List the services in the stack
   tasks       List the tasks in the stack