[BeePrint enhancement] mDNS responder from alf45tar

https://github.com/xreef/MKS_WIFI_upgrade_with_BeePrint_web_interface/issues/5 The WiFi printer screen does not display the Printer Number as in the original firmware. Not a bug because it is not used anywhere. May I suggest to implement the mDNS responder in order to use the name instead of the IP that can change due to DHCP? Thanks alf45tar