update env and readme for creality-discovery

Author: springhack

creality-discovery/README.md

@@ -1,7 +1,13 @@
 # Auto Discovery Creality Device And Forward TCP
 
 ### Config Envs
-- `CR_SN`: printer sn, eg: `1234567890ABCD`
+- `CR_ID`: printer id, eg: `1234567890ABCD`
 - `CR_IFACE`: which network interface to scan
 - `CR_PORTS`: tcp ports to forward, eg: `4408,8000`
 - `CR_INTERVAL`: how often to scan, eg: `10`
+
+### Get `CR_ID`
+> Servel ways, eg: mobile app info, ssh or `Creality Print` desktip client
+
+![](creality-ssh.png)
+![](creality-print.png)

creality-discovery/creality-print.png

@@ -36,7 +36,7 @@ func info(format string, v ...interface{}) {
 func init() {
 	log.SetOutput(io.Discard) // 彻底禁言标准库
 	cfg = Config{
-		TargetService: fmt.Sprintf("_Creality-%s._udp", getEnv("CR_SN", "1234567890ABCD")),
+		TargetService: fmt.Sprintf("_Creality-%s._udp", getEnv("CR_ID", "1234567890ABCD")),
 		BindIface:     getEnv("CR_IFACE", "host0"),
 		ProxyPorts:    strings.Split(getEnv("CR_PORTS", "4408,8000"), ","),
 		ScanInterval:  time.Duration(getEnvInt("CR_INTERVAL", 10)) * time.Second,