Add device_class section into Modbus sensor and binary sensor docs (#11496)

source/_integrations/binary_sensor.modbus.markdown

@@ -52,6 +52,11 @@ coils:
       description: Coil number.
       required: true
       type: integer
+    device_class:
+      description: The [type/class](/integrations/binary_sensor/#device-class) of the binary sensor to set the icon in the frontend.
+      required: false
+      type: device_class
+      default: None
 {% endconfiguration %}
 
 It's possible to change the default 30 seconds scan interval for the sensor updates as shown in the [Platform options](/docs/configuration/platform_options/#scan-interval) documentation.

source/_integrations/sensor.modbus.markdown

@@ -73,6 +73,11 @@ registers:
       description: Unit to attach to value.
       required: false
       type: integer
+    device_class:
+      description: The [type/class](/integrations/sensor/#device-class) of the sensor to set the icon in the frontend.
+      required: false
+      type: device_class
+      default: None
     count:
       description: Number of registers to read.
       required: false