Updated the modules doxygen page

doc/modules

@@ -1,6 +1,16 @@
 /**
  * @anchor modules_anchor
  *
+ * @defgroup constructs C++ Constructs Used by All Modules
+ * \brief These are C++ constructs defined by the modules.
+ *
+ * @defgroup constants Constants
+ * @brief Constants you can change
+ *
+ * @defgroup utils Utils
+ * @brief The utils directory is for various programs and scripts related 
+ * to code coverage, test suites, style checking, and benchmarking.
+ *
  * @defgroup core Core
  * \brief The "core" module contains:
  *    - a time management class to hold a time and convert between various time units: ns3::Time 
@@ -33,8 +43,6 @@
  *    - models which abstract the application-layer API: ns3::Application,
  *      ns3::Socket, ns3::SocketFactory, and, ns3::Udp
  * 
- * @defgroup devices Devices
- *
  * @defgroup internet Internet
  * 
  * The "internet" module contains:
@@ -43,16 +51,7 @@
  *    - an ARP module
  *    - a UDP and a TCP implementation
  *    
- * @defgroup routing Routing
- *
  * @defgroup applications Applications
  *
  * @defgroup mobility Mobility
- *
- * @defgroup constants Constants
- * @brief Constants you can change
- *
- * @defgroup utils Utils
- * @brief The utils directory is for various programs and scripts related 
- * to code coverage, test suites, style checking, and benchmarking.
  */