fix some dox warnings

doc/modules

@@ -15,12 +15,13 @@
  *    - a class to register regression tests with the test manager: ns3::Test and ns3::TestManager
  *    - debugging facilities: \ref logging, \ref assert, \ref error
  *    - \ref randomvariable
+ *    - a base class for objects which need to support per-instance "attributes" and
+ *      trace sources: ns3::ObjectBase
  *    - a base class for objects which need to support reference counting
- *      and QueryInterface: ns3::Object and ns3::InterfaceId 
- *    - a set of low-level trace facilities integrated in the ns3::Object system: \ref tracing
- *    - a ns3::ComponentManager which can be used to manage the creation
- *      of any object which derives from ns3::Object through an ns3::ClassId 
+ *      and dynamic object aggregation: ns3::Object
  *    - a smart-pointer class ns3::Ptr designed to work together with ns3::Object
+ *    - a configuration class used to set and control all attributes and trace sources
+ *      in a simulation: ns3::Config.
  *
  * @defgroup common Common
  * The "core" module contains: 
@@ -61,5 +62,4 @@
  * @brief Constants you can change
  *
  * @defgroup contrib Contrib
- */
-
+ */