Add light white parameter to light/services.yaml (#53075)

homeassistant/components/light/services.yaml

@@ -265,6 +265,17 @@ turn_on:
           min: -100
           max: 100
           unit_of_measurement: "%"
+    white:
+      name: White
+      description:
+        Set the light to white mode and change its brightness, where 0 turns
+        the light off, 1 is the minimum brightness and 255 is the maximum
+        brightness supported by the light.
+      advanced: true
+      selector:
+        number:
+          min: 0
+          max: 255
     profile:
       name: Profile
       description: Name of a light profile to use.