doc: Fix the Doxygen section endings

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/include/osmocom/core/socket.h b/include/osmocom/core/socket.h
index 8821463..f15a03a 100644
--- a/include/osmocom/core/socket.h
+++ b/include/osmocom/core/socket.h
@@ -30,6 +30,6 @@
 
 int osmo_sockaddr_is_local(struct sockaddr *addr, unsigned int addrlen);
 
-/*! }@ */
+/*! @} */
 
 #endif /* _OSMOCORE_SOCKET_H */