dt-bindings: iio: chemical: sensirion,scd4x: Add yaml description

Add documentation for the SCD4x carbon dioxide sensor from Sensirion.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Roan van Dijk <roan@protonic.nl>
Link: https://lore.kernel.org/r/20211008101706.755942-2-roan@protonic.nlSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/chemical/sensirion,scd4x.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/chemical/sensirion,scd4x.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Sensirion SCD4X carbon dioxide sensor
+
+maintainers:
+  - Roan van Dijk <roan@protonic.nl>
+
+description: |
+  Air quality sensor capable of measuring co2 concentration, temperature
+  and relative humidity.
+
+properties:
+  compatible:
+    enum:
+      - sensirion,scd40
+      - sensirion,scd41
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  vdd-supply: true
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      co2-sensor@62 {
+        compatible = "sensirion,scd41";
+        reg = <0x62>;
+      };
+    };