Ethernet e Link (Arduino)

#include <SPI.h>
#include <String.h>
#include <Ethernet.h>

byte mac[] = { 0x90, 0xA2, 0xDA, 0x00, 0x9B, 0x36 };
byte ip[] = { 192, 168, 0, 91 };
EthernetServer server(8090);

String readString = String(30);

void setup() {
  Ethernet.begin(mac, ip);
}

void loop() {

  EthernetClient client = server.available();

  if(client)
  {
    while(client.connected())
    {
      if(client.available())
      {
        char c = client.read();

        if(readString.length() < 30) {
          readString += (c);
        }

        if(c == '\n')
        {
          // cabeçalho http padrão
          client.println("HTTP/1.1 200 OK");
          client.println("Content-Type: text/html");
          client.println();

          client.println("<!doctype html>");
          client.println("<html>");
          client.println("<head>");
          client.println("<title>Exemplo Link</title>");
          client.println("<meta name=\"viewport\" content=\"width=device-width, initial-scale=1\">");
          client.println("<meta charset=\"utf-8\">");
          client.println("</head>");
          client.println("<body>");
          client.println("<center>");

          client.println("<h1>Exemplo de link - Arduino e Ethernet</h1>");
          // no html seria assim:  <a href="https://www.google.com.br">Acesse o Google</a>

          // então no arduino fica assim
          client.println("<a href=\"https://www.youtube.com/user/TecnoEduardo\">Visite o link aqui!</a>");

          client.println("</center>");
          client.println("</body>");
          client.println("</html>");

          readString = "";

          client.stop();
        }
      }

    }
  }

}