Merge pull request #23039 from yongtang/05262016-docs-cluster-store-opts

Fix error in dockerd.md for incorrect cluster-store-opts example.
(cherry picked from commit f1276cd3aa8d2bff6e3ab1ac3a175deeecac405e)

Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au>

docs/reference/commandline/daemon.md

@@ -896,7 +896,7 @@ This is a full example of the allowed configuration options in the file:
 	"pidfile": "",
 	"graph": "",
 	"cluster-store": "",
-	"cluster-store-opts": [],
+	"cluster-store-opts": {},
 	"cluster-advertise": "",
 	"debug": true,
 	"hosts": [],