feat: add pipefunc cache example

[egorchakov]

https://pipefunc.readthedocs.io/en/stable/tutorial/

If calling the pipeline like a function (in contrast to using pipeline.map) keys of the cache are always in terms of the root arguments of the pipeline. When using pipeline.map, the keys are in terms of the arguments of the function.
The key is constructed from the function name and the (root) arguments passed to the function. If the arguments are not hashable, the pipefunc.cache.to_hashable function is used to attempt to convert them to a hashable form.