Add LLMNR next to mDNS

[JakubKohoutek]

Hi tttapa, first of all - great work with the beginner's guide, it's awesome, thank you.

I have a small improvement proposal - I was trying the mDNS and I realized that Windows machines are not compatible with this standard out of the box, it works only if some third party software is installed on windows machine. This is a little unfortunate, but I found it is possible to add LLMNR responder to the esp8266, which is compatible with Windows. There's even a library for that: https://github.com/esp8266/Arduino/tree/master/libraries/ESP8266LLMNR

I would propose to add to your mDNS section also a note about LLMNR - its usage is as simple as importing the library and then calling one function in the setup:

#include <esp8266LLMNR.h>
void setup() {
  // when the network connection is estabilished:
  LLMNR.begin("esp8266");
}

I tried it and both mDNS and LLMNR can coexist together, so it might be good to have both of them to support wider range of devices:

  const char* DOMAIN_NAME = "esp8266";
  MDNS.begin(DOMAIN_NAME);
  LLMNR.begin(DOMAIN_NAME);