[doc] make sure all SMS related code is part of the 'sms' group

Change-Id: I24c56ccb56d5b39cfb887808f91b715da54c0f8b
diff --git a/src/gsm/gsm0411_smc.c b/src/gsm/gsm0411_smc.c
index 7414e95..f7c536b 100644
--- a/src/gsm/gsm0411_smc.c
+++ b/src/gsm/gsm0411_smc.c
@@ -1,5 +1,4 @@
-/*! \file gsm0411_smc.c
- * Point-to-Point (PP) Short Message Service (SMS).
+/* Point-to-Point (PP) Short Message Service (SMS).
  * Support on Mobile Radio Interface
  * 3GPP TS 04.11 version 7.1.0 Release 1998 / ETSI TS 100 942 V7.1.0. */
 /*
@@ -63,6 +62,7 @@
 
 /*! \addtogroup sms
  *  @{
+ *  \file gsm0411_smc.c
  *  Point-to-Point (PP) Short Message Service (SMS) as per TS 04.11
  */