DHT11 Sensor Code Fatal Error
The examples I can see from Adafruit say

#include "DHT.h"


or

#include &lt;DHT.h&gt;


But you wrote

#include &lt;dht.h&gt;


They aren't the same.

Further, the examples for the Adafruit library show usage like:

  // Reading temperature or humidity takes about 250 milliseconds!
  // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
  float h = dht.readHumidity();
  // Read temperature as Celsius (the default)
  float t = dht.readTemperature();
  // Read temperature as Fahrenheit (isFahrenheit = true)
  float f = dht.readTemperature(true);


But you call DHT.temperature and DHT.humidity.

If you are meaning to use the Adafruit library, you have to write your code according to their documentation.

Also of note, you have defined the type of the object as dht and the name as DHT, but for Adafruit, the type is DHT.

EDIT:

The example on the website you note has a downloadable zip file for the DHT library they use. You cannot assume that all libraries for interfacing a certain sensor will all have the same programming interface.