Nits: fix DNS resolution message. Add Makefile comment for testing targets

src/dns.c

@@ -161,7 +161,8 @@ static void dns_cb(struct mg_connection *c, int ev, void *ev_data,
           if (dm.resolved) {
             dm.addr.port = d->c->rem.port;  // Save port
             d->c->rem = dm.addr;            // Copy resolved address
-            MG_DEBUG(("%lu %s is %M", d->c->id, dm.name, mg_print_ip, &c->rem));
+            MG_DEBUG(
+                ("%lu %s is %M", d->c->id, dm.name, mg_print_ip, &d->c->rem));
             mg_connect_resolved(d->c);
 #if MG_ENABLE_IPV6
           } else if (dm.addr.is_ip6 == false && dm.name[0] != '\0' &&