dt-bindings: iio: chemical: add Atlas Scientific RTD-SM sensor docs

Cc: devicetree@vger.kernel.org
Signed-off-by: Matt Ranostay <matt.ranostay@konsulko.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/chemical/atlas,sensor.yaml

@@ -17,6 +17,7 @@ description: |
     http://www.atlas-scientific.com/_files/_datasheets/_oem/EC_oem_datasheet.pdf
     http://www.atlas-scientific.com/_files/_datasheets/_oem/ORP_oem_datasheet.pdf
     http://www.atlas-scientific.com/_files/_datasheets/_oem/pH_oem_datasheet.pdf
+    http://www.atlas-scientific.com/_files/_datasheets/_oem/RTD_oem_datasheet.pdf
 
 properties:
   compatible:
@@ -25,6 +26,7 @@ properties:
       - atlas,ec-sm
       - atlas,orp-sm
       - atlas,ph-sm
+      - atlas,rtd-sm
 
   reg:
      maxItems: 1