Cleanup: preview rendering, update assumptions in comment

The `action_preview_render()` function used to just render, but now it
also temporarily applies the pose. Its comment is now updated for this.

No functional changes.

source/blender/editors/render/render_preview.c

@@ -861,9 +861,9 @@ static void action_preview_render_cleanup(IconPreview *preview, struct PoseBacku
   DEG_id_tag_update(&preview->active_object->id, ID_RECALC_GEOMETRY);
 }
 
-/* Render a pose. It is assumed that the pose has already been applied and that the scene camera is
- * capturing the pose. In other words, this function just renders from the scene camera without
- * evaluating the Action stored in preview->id. */
+/* Render a pose from the scene camera. It is assumed that the scene camera is
+ * capturing the pose. The pose is applied temporarily to the current object
+ * before rendering. */
 static void action_preview_render(IconPreview *preview, IconPreviewSize *preview_sized)
 {
   char err_out[256] = "";