Correction/Addition of new IOT code for ESP8266

[Saru13]

Here:
......
#ifdef USE_DHT
// Install "DHT sensor library" if you get an error
#include <DHT.h>
// Change D3 to the pin you've connected your sensor to
//#define DHTPIN D3
#define DHTPIN 2
......

Defining the pin will not always include the "D". ("That's what she said.")
For a generic ESP8266 (ESP-01), you'll need to define the pin as a number as per above.