[doc] Make sure loggingrb.c file is in correct Doxygen group.

loggingrb.c, like loggingrb.h should be part of the loggingrb group!

Change-Id: I4822a46631b45df1afda202c00038b6ad2c8b5ae
diff --git a/src/loggingrb.c b/src/loggingrb.c
index 5127a2f..b7d8d1f 100644
--- a/src/loggingrb.c
+++ b/src/loggingrb.c
@@ -20,7 +20,7 @@
  *
  */
 
-/*! \addtogroup logging
+/*! \addtogroup loggingrb
  *  @{
  * \file loggingrb.c */