doc: Fix the Doxygen section endings

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/src/signal.c b/src/signal.c
index 7ddc2e0..6384384 100644
--- a/src/signal.c
+++ b/src/signal.c
@@ -106,4 +106,4 @@
 	}
 }
 
-/*! }@ */
+/*! @} */