When point/curves count of a `GreasePencilDrawing` is changed, prior stroke
slices are no longer valid. This is not obvious when using the `stroke()`
call since it is meant to provide a easier access to the drawing data and
did not represent the actual data layout in the drawing, hence we need an
additional note in the document to tell users to be more careful.
Pull Request: https://projects.blender.org/blender/blender/pulls/126815
c5bdaaf96c