Add playground objects

children.json

@@ -20,6 +20,9 @@
             "node[kids_area];",
             "way[kids_area];",
             "relation[kids_area];",
+            "node[playground];",
+            "way[playground];",
+            "relation[playground];",
             ");"
         ]
     },
@@ -81,4 +84,4 @@
         "  </tr>",
         "</table>"
     ]
-}
+}