manpage: fix lintian warnings

Description: extraneous slash caused this lintian warning:
  W: iptables: manpage-has-errors-from-man usr/share/man/man8/iptables.8.gz
     220: cannot use newline as a starting delimiter
  W: iptables: manpage-has-errors-from-man usr/share/man/man8/ip6tables.8.gz
     1823: warning: `precedence'' not defined

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/iptables.8.in b/iptables.8.in
index 14fc23a..cb6e6b0 100644
--- a/iptables.8.in
+++ b/iptables.8.in
@@ -217,7 +217,7 @@
 Rename the user specified chain to the user supplied name.  This is
 cosmetic, and has no effect on the structure of the table.
 .TP
-\fB\-\h\fP
+\fB\-h\fP
 Help.
 Give a (currently very brief) description of the command syntax.
 .SS PARAMETERS