[Python] Recipe showing how to use the filename callback to generate new files every time write_dataset is called

Inspired by: https://stackoverflow.com/questions/69184289/pyarrow-overwrites-dataset-when-using-s3-filesystem/69185178#69185178

Search the cookbook for existing Python dataset recipes and the write_dataset entry point, then read the linked Stack Overflow example for the intended filename-callback behavior. Done means a documented recipe demonstrates that repeated write_dataset calls create new files rather than overwriting the dataset.

Written by the indexing model from the issue text.