doc: Fix the Doxygen section endings

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/include/osmocom/core/conv.h b/include/osmocom/core/conv.h
index e76a5c6..e5b2a97 100644
--- a/include/osmocom/core/conv.h
+++ b/include/osmocom/core/conv.h
@@ -141,6 +141,6 @@
                      const sbit_t *input, ubit_t *output);
 
 
-/*! }@ */
+/*! @} */
 
 #endif /* __OSMO_CONV_H__ */