[DOC] Update Example for Converting Model to Flow

[jgyasu]

https://openml.github.io/openml-python/latest/examples/Basics/simple_flows_and_runs_tutorial/#upload-the-machine-learning-experiments-to-openml describes the process to upload models as flows, it asks the user to manually create a OpenMLFlow object and fill in the metadata. But the flows should be automatically generated from the models using the function openml.flows.create_flow_from_model as per the docstring of OpenMLFlow class.

It should be verified if the flows can be generated automatically or not and if they can be then it should be updated in the document.