BUG/MINOR: dns: Fix CLI keyword declaration

The cli command to show resolvers stats is in conflict with the command to show
proxies and servers stats. When you use the command "show stat resolvers [id]",
instead of printing stats about resolvers, you get the stats about all proxies
and servers.

Now, to avoid conflict, to print resolvers stats, you must use the following
command:

     show resolvers [id]

This patch must be backported in 1.7.
diff --git a/src/dns.c b/src/dns.c
index dbb473e..aa17846 100644
--- a/src/dns.c
+++ b/src/dns.c
@@ -2248,9 +2248,9 @@
 {
 	struct dns_resolvers *presolvers;
 
-	if (*args[3]) {
+	if (*args[2]) {
 		list_for_each_entry(presolvers, &dns_resolvers, list) {
-			if (strcmp(presolvers->id, args[3]) == 0) {
+			if (strcmp(presolvers->id, args[2]) == 0) {
 				appctx->ctx.cli.p0 = presolvers;
 				break;
 			}
@@ -2675,12 +2675,13 @@
 }
 
 /* register cli keywords */
-static struct cli_kw_list cli_kws = {{ },{
-	{ { "show", "stat", "resolvers", NULL }, "show stat resolvers [id]: dumps counters from all resolvers section and\n"
-	                                         "                          associated name servers",
-	                                         cli_parse_stat_resolvers, cli_io_handler_dump_resolvers_to_buffer },
-	{{},}
-}};
+static struct cli_kw_list cli_kws = {{ }, {
+		{ { "show", "resolvers", NULL }, "show resolvers [id]: dumps counters from all resolvers section and\n"
+		  "                     associated name servers",
+		  cli_parse_stat_resolvers, cli_io_handler_dump_resolvers_to_buffer },
+		{{},}
+	}
+};
 
 
 __attribute__((constructor))