doc: resynchronize manpage with in-code help

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
diff --git a/ip6tables.8.in b/ip6tables.8.in
index 3d19a4c..a31887e 100644
--- a/ip6tables.8.in
+++ b/ip6tables.8.in
@@ -30,16 +30,16 @@
 \fBip6tables\fP [\fB\-t\fP \fItable\fP] {\fB\-A\fP|\fB\-D\fP} \fIchain
 rule-specification\fP [\fIoptions...\fP]
 .PP
-\fBip6tables\fP [\fB\-t\fP \fItable\fP] \fB\-I\fP [\fIrulenum\fP]
+\fBip6tables\fP [\fB\-t\fP \fItable\fP] \fB\-I\fP \fIchain\fP [\fIrulenum\fP]
 \fIrule-specification\fP [\fIoptions...\fP]
 .PP
-\fBip6tables\fP [\fB\-t\fP \fItable\fP] \fB\-R\fP \fIrulenum
+\fBip6tables\fP [\fB\-t\fP \fItable\fP] \fB\-R\fP \fIchain rulenum
 rule-specification\fP [\fIoptions...\fP]
 .PP
 \fBip6tables\fP [\fB\-t\fP \fItable\fP] \fB\-D\fP \fIchain rulenum\fP
 [\fIoptions...\fP]
 .PP
-\fBip6tables\fP [\fB\-t\fP \fItable\fP] \fB\-S\fP [\fIchain\fP]
+\fBip6tables\fP [\fB\-t\fP \fItable\fP] \fB\-S\fP [\fIchain\fP [\fIrulenum\fP]]
 .PP
 \fBip6tables\fP [\fB\-t\fP \fItable\fP] {\fB\-F\fP|\fB\-L\fP|\fB\-Z\fP}
 [\fIchain\fP] [\fIoptions...\fP]