iptables: libxt_string.man add examples

Add usage examples for string and hex string patterns.

References: http://bugs.debian.org/699904
Signed-off-by: Laurence J. Lane <ljlane@debian.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
diff --git a/extensions/libxt_string.man b/extensions/libxt_string.man
index b6b271d..adc9c18 100644
--- a/extensions/libxt_string.man
+++ b/extensions/libxt_string.man
@@ -16,3 +16,13 @@
 .TP
 [\fB!\fP] \fB\-\-hex\-string\fP \fIpattern\fP
 Matches the given pattern in hex notation.
+.TP
+Examples:
+.IP
+# The string pattern can be used for simple text characters.
+.br
+iptables \-A INPUT \-p tcp \-\-dport 80 \-m string \-\-algo bm \-\-string 'GET /index.html' \-j LOG
+.IP
+# The hex string pattern can be used for non-printable characters, like |0D 0A| or |0D0A|.
+.br
+iptables \-p udp \-\-dport 53 \-m string \-\-algo bm \-\-from 40 \-\-to 57 \-\-hex\-string '|03|www|09|netfilter|03|org|00|'