Add cloud operations track (#10)

* Add cloud operatios track

* Add back object meta

* Add unlisted pages

Author: cristian-paris

docs/cloud_operations/docker/_category_.json

@@ -0,0 +1,9 @@
+{
+    "label": "Docker",
+    "position": 2,
+    "link": {
+      "type": "generated-index",
+      "description": "Simple Guide to Docker"
+    }
+  }
+