add a reference to the lock file
diff --git a/ebtables.8 b/ebtables.8
index 001aa35..81d1cf6 100644
--- a/ebtables.8
+++ b/ebtables.8
@@ -1103,6 +1103,7 @@
 .br
 .SH FILES
 .I /etc/ethertypes
+.I $(LOCKFILE)
 .SH ENVIRONMENT VARIABLES
 .I EBTABLES_ATOMIC_FILE
 .SH MAILINGLISTS