blender-manual/manual/render/shader_nodes/color/rgb_curves.rst

Sphinx Warnings

3: ERROR: Error in "warning" directive:
unknown option: "start-after".

.. warning:: include not available in preview:  /compositing/types/color/rgb_curves.rst
   :start-after: .. --- copy below this line ---

Note the preview is not accurate and warnings may not indicate real issues.