Merge pull request #1024 from moxiegirl/add_id_install

Troubleshooting revealed need id if title is the same

docs/install-w-machine.md

@@ -4,6 +4,7 @@ title = "Docker Swarm"
 description = "Swarm release notes"
 keywords = ["docker, swarm, clustering, discovery, release,  notes"]
 [menu.main]
+identifier="swm_install"
 parent="mn_install"
 weight=9
 +++