[MQ2] Gas sensor & tweak DHT config to avoid editing source when PIN is different (#1576)

Add MQ2 Gas sensor & tweak DHT config to avoid editing source when PIN is different

docs/prerequisites/board.md

@@ -4,7 +4,7 @@ OpenMQTTGateway is not closed to one board or type of board, by using the power
 
 You can take a look to the [OpenMQTTGateway compatible website](https://compatible.openmqttgateway.com) to have a view of the [supported boards](https://compatible.openmqttgateway.com/index.php/boards/).
 
-Moreover the gateways capacities can be extended with sensors; DHT, HC SR501, ADC, I2C bus, INA226, TEMT6000, TSL2561, BME280/BMP280, HTU21D, AHTx0, DS1820
+Moreover the gateways capacities can be extended with sensors; DHT, HC SR501, ADC, I2C bus, INA226, MQ2, TEMT6000, TSL2561, BME280/BMP280, HTU21D, AHTx0, DS1820
 or actuators; LED, relays, PWM.
 
 ::: tip Running on a computer

docs/setitup/sensors.md

@@ -12,6 +12,7 @@
 |GPIO Input|Inputs|-|
 |GPIO KeyCode|Keycode|[parts list](https://compatible.openmqttgateway.com/index.php/parts)|
 |INA226|Current, Voltage|[parts list](https://compatible.openmqttgateway.com/index.php/parts)|
+|MQ2|Gas (flammable)|[parts list](https://compatible.openmqttgateway.com/index.php/parts)|
 |TEMT6000|Luminosity|[parts list](https://compatible.openmqttgateway.com/index.php/parts)|
 |TSL2561|Luminosity|[parts list](https://compatible.openmqttgateway.com/index.php/parts)|
 
@@ -29,6 +30,7 @@
 |HTU21 SCL|A5|D1|22|
 |INA226 SDA|A4|D2|21|
 |INA226 SCL|A5|D1|22|
+|MQ02 |A0 + D4|A0 + D4|A0 + D4|
 |TEMT6000 |A0|A0|A0|
 |TSL2561 SDA|A4|D2|21|
 |TSL2561 SCL|A5|D1|22|