[Containment] Add bundle declaration

WTD-962.

platform/containment/bundle.json

@@ -0,0 +1,11 @@
+{
+    "extensions": {
+        "policies": [
+            {
+                "category": "composition",
+                "implementation": "CompositionPolicy.js",
+                "depends": [ "typeService", "capabilityService" ]
+            }
+        ]
+    }
+}

platform/containment/src/CapabilityTable.js

@@ -8,7 +8,9 @@ define(
 
         /**
          * Build a table indicating which types are expected to expose
-         * which capabilities.
+         * which capabilities. This supports composition policy (rules
+         * for which objects can contain which other objects) which
+         * sometimes is determined based on the presence of capabilities.
          */
         function CapabilityTable(typeService, capabilityService) {
             var table = {};