Update README.md

Correct example

Author: sandeepmistry

README.md

@@ -13,10 +13,10 @@ Connect to a NTP server, here is how:
 const char *ssid     = "<SSID>";
 const char *password = "<PASSWORD>";
 
-WiFiUDP ntpUDP(ntpUDP);
+WiFiUDP ntpUDP;
 
 // By default 'time.nist.gov' is used.
-NTPClient timeClient;
+NTPClient timeClient(ntpUDP);
 
 // You can specify the time server pool and the offset, (in seconds)
 // additionaly you can specify the update interval (in milliseconds).