Usage with multiple Sensors

* add sample code with description to README
* sample code shows how to connect two SHT31 sensors

README.md

@@ -67,3 +67,62 @@ void loop() {
   delay(1000);
 }
 ```
+
+### Usage with two SHT31 sensors
+
+```c++
+#include <Wire.h>
+#include "SHTSensor.h"
+
+// Sensor with normal i2c address
+// Sensor 1 with address pin pulled to GND
+SHTSensor sht1(SHTSensor::SHT3X);
+
+// Sensor with alternative i2c address
+// Sensor 2 with address pin pulled to Vdd
+SHTSensor sht2(SHTSensor::SHT3X_ALT);
+
+void setup() {
+  // put your setup code here, to run once:
+  Wire.begin();
+  Serial.begin(9600);
+  delay(1000); // let serial console settle
+
+  // init on a specific sensor type (i.e. without auto detecting), 
+  // does not check if the sensor is responding and will thus always succeed.
+
+  // initialize sensor with normal i2c-address
+  sht1.init();
+
+  // initialize sensor with alternative i2c-address
+  sht2.init();
+}
+void loop() {
+  // put your main code here, to run repeatedly:
+  // read from first sensor
+  if (sht1.readSample()) {
+    Serial.print("SHT1 :\n");
+    Serial.print("  RH: ");
+    Serial.print(sht1.getHumidity(), 2);
+    Serial.print("\n");
+    Serial.print("  T:  ");
+    Serial.print(sht1.getTemperature(), 2);
+    Serial.print("\n");
+  } else {
+    Serial.print("Sensor 1: Error in readSample()\n");
+  }
+  // read from second sensor
+  if (sht2.readSample()) {
+    Serial.print("SHT2:\n");
+    Serial.print("  RH: ");
+    Serial.print(sht2.getHumidity(), 2);
+    Serial.print("\n");
+    Serial.print("  T:  ");
+    Serial.print(sht2.getTemperature(), 2);
+    Serial.print("\n");
+  } else {
+    Serial.print("Sensor 2: Error in readSample()\n");
+  }
+  delay(1000);
+}
+```