message: Updated framebuffer doc to reflect actual normal channel behavior
diff: @@ -2753,7 +2753,7 @@ values of `OSPFrameBufferChannel` listed in the table below.
  OSP_FB_DEPTH euclidean distance to the camera (_not_ to the image plane), as linear 32\ bit float; for multiple samples per pixel their minimum is taken
  OSP_FB_ACCUM accumulation buffer for progressive refinement
  OSP_FB_VARIANCE for estimation of the current noise level if OSP_FB_ACCUM is also present, see [rendering]
  - OSP_FB_NORMAL accumulated world-space normal of the first hit, as vec3f
  + OSP_FB_NORMAL accumulated world-space normal of the first non-specular hit, as vec3f
  OSP_FB_ALBEDO accumulated material albedo (color without illumination) at the first hit, as vec3f
  ---------------- -----------------------------------------------------------
  : Framebuffer channels constants (of type `OSPFrameBufferChannel`),
  