Add warning in transit tuto on SequenceParallel API

[lgrcia]

At the end of https://prose.readthedocs.io/en/latest/ipynb/casestudies/transit.html#multiprocessing-alternative , put a warning about the data_blocks like:

If not passed as data_blocks (second attribute of SequenceParallel), a block will not retain attributes. Any blocks whose attributes must be accessed (like GetFluxes or SelectiveStack) must be in the data_blocks list.

[lgrcia]

@mathtimm do you think that sentence helps? Just as to make the info pop out (everyone miss that)

[lgrcia]

Also add how to acces the fluxes in the data_blocks with .data[i] so that user know the difference with Sequence. There should be a link to this last section in the SequenceParallel docstrings (because it is more illustrative)

[mathtimm]

@mathtimm do you think that sentence helps? Just as to make the info pop out (everyone miss that)

Yes, definitely, and it would be nice to also show in the tutorial how to access it, just like you said: fluxes: Fluxes = faster_photometry.data[-1].fluxes