dt-binding: iio: Add documentation for AD7091R5

Documentation for AD7091R5 ADC was added.
Signed-off-by: Beniamin Bia <beniamin.bia@analog.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/adc/adi,ad7091r5.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/adi,ad7091r5.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices AD7091R5 4-Channel 12-Bit ADC
+
+maintainers:
+  - Beniamin Bia <beniamin.bia@analog.com>
+
+description: |
+  Analog Devices AD7091R5 4-Channel 12-Bit ADC
+  https://www.analog.com/media/en/technical-documentation/data-sheets/ad7091r-5.pdf
+
+properties:
+  compatible:
+    enum:
+      - adi,ad7091r5
+
+  reg:
+    maxItems: 1
+
+  vref-supply:
+    description:
+      Phandle to the vref power supply
+
+  interrupts:
+    maxItems: 1
+
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@2f {
+                compatible = "adi,ad7091r5";
+                reg = <0x2f>;
+
+                interrupts = <25 IRQ_TYPE_EDGE_FALLING>;
+                interrupt-parent = <&gpio>;
+        };
+    };
+...