[NETFILTER]: statistic match: add missing Kconfig help text

Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/netfilter/Kconfig

@@ -411,7 +411,10 @@ config NETFILTER_XT_MATCH_STATISTIC
 	tristate '"statistic" match support'
 	depends on NETFILTER_XTABLES
 	help
-	  statistic module
+	  This option adds a `statistic' match, which allows you to match
+	  on packets periodically or randomly with a given percentage.
+
+	  To compile it as a module, choose M here.  If unsure, say N.
 
 config NETFILTER_XT_MATCH_STRING
 	tristate  '"string" match support'