message: Fix typo "luminous"
diff: @@ -1874,7 +1874,7 @@ thus individual flakes are not visible.
  The [path tracer] supports the Luminous material which emits light
  uniformly in all directions and which can thus be used to turn any
  geometric object into a light source. It is created by passing the type
  -string "`Luminous`" to `ospNewMaterial`. The amount of constant
  +string "`luminous`" to `ospNewMaterial`. The amount of constant
  radiance that is emitted is determined by combining the general
  parameters of lights: [`color` and `intensity`](#lights).
  