chore: Make slash optional for system resolver

config/config.go

@@ -974,6 +974,10 @@ func parsePureDNSServer(server string) string {
 		return "udp://" + server
 	}
 
+	if server == "system" {
+		return "system://"
+	}
+
 	if ip, err := netip.ParseAddr(server); err != nil {
 		if strings.Contains(server, "://") {
 			return server

docs/config.yaml

@@ -177,7 +177,7 @@ dns:
     - 8.8.8.8
     - tls://1.12.12.12:853
     - tls://223.5.5.5:853
-    - system://  # append DNS server from system configuration. If not found, it would print an error log and skip.
+    - system  # append DNS server from system configuration. If not found, it would print an error log and skip.
   enhanced-mode: fake-ip # or redir-host
   
   fake-ip-range: 198.18.0.1/16 # fake-ip 池设置