doc: Fix the Doxygen section endings

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/include/osmocom/vty/telnet_interface.h b/include/osmocom/vty/telnet_interface.h
index 65a1dd9..3c22201 100644
--- a/include/osmocom/vty/telnet_interface.h
+++ b/include/osmocom/vty/telnet_interface.h
@@ -51,6 +51,6 @@
 
 void telnet_exit(void);
 
-/*! }@ */
+/*! @} */
 
 #endif /* TELNET_INTERFACE_H */