ranap_msg_factory: add missing apidoc

The functions ranap_new_msg_iu_rel_req and ranap_new_msg_rab_rel_req
lack apidoc strings.

Change-Id: I7484413980acdf17fde9ed0f97cf7f97e0ef3ae4

src/ranap_msg_factory.c

@@ -876,6 +876,7 @@ struct msgb *ranap_new_msg_rab_assign_data(uint8_t rab_id, uint32_t gtp_ip,
 	return msg;
 }
 
+/*! \brief generate RANAP IU RELEASE REQUEST message */
 struct msgb *ranap_new_msg_iu_rel_req(const RANAP_Cause_t *cause)
 {
 	RANAP_Iu_ReleaseRequestIEs_t ies;
@@ -905,6 +906,7 @@ struct msgb *ranap_new_msg_iu_rel_req(const RANAP_Cause_t *cause)
 	return msg;
 }
 
+/*! \brief generate RANAP RAB RELEASE REQUEST message */
 struct msgb *ranap_new_msg_rab_rel_req(uint8_t rab_id, const RANAP_Cause_t *cause)
 {
 	RANAP_RAB_ReleaseItemIEs_t item_ies;