doc: escape minus sign in manpages
groff formats '-' as a hyphen, and '\-' is needed for a minus.
Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/extensions/libxt_length.man b/extensions/libxt_length.man
index 27236ae..e324e03 100644
--- a/extensions/libxt_length.man
+++ b/extensions/libxt_length.man
@@ -2,4 +2,4 @@
f a packet against a specific value
or range of values.
.TP
-[\fB!\fP] \fB--length\fP \fIlength\fP[\fB:\fP\fIlength\fP]
+[\fB!\fP] \fB\-\-length\fP \fIlength\fP[\fB:\fP\fIlength\fP]