Tidy up \file & \author blocks under core/net/ipv6

* Make these blocks appear in the respective module pages
* Re-word \file blocks to bring them up to speed with what each file actually does nowadays

core/net/ipv6/uip6.c

@@ -31,20 +31,20 @@
  *
  */
 
+/**
+ * \addtogroup uip6
+ * @{
+ */
+
 /**
  * \file
- *         The uIP TCP/IPv6 stack code.
+ *    The uIP TCP/IPv6 stack code.
  *
  * \author Adam Dunkels <adam@sics.se>
  * \author Julien Abeille <jabeille@cisco.com> (IPv6 related code)
  * \author Mathilde Durvy <mdurvy@cisco.com> (IPv6 related code)
  */
 
-/**
- * \addtogroup uip6
- * @{
- */
-
 /*
  * uIP is a small implementation of the IP, UDP and TCP protocols (as
  * well as some basic ICMP stuff). The implementation couples the IP,