doc: Fix the Doxygen section endings

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/include/osmocom/gsm/abis_nm.h b/include/osmocom/gsm/abis_nm.h
index 5b5bff0..cc01765 100644
--- a/include/osmocom/gsm/abis_nm.h
+++ b/include/osmocom/gsm/abis_nm.h
@@ -35,6 +35,6 @@
 int abis_nm_chcomb4pchan(enum gsm_phys_chan_config pchan);
 enum abis_nm_chan_comb abis_nm_pchan4chcomb(uint8_t chcomb);
 
-/*! }@ */
+/*! @} */
 
 #endif /* _OSMO_GSM_ABIS_NM_H */