[Documentation]: Update parallel I/O and iterative write tutorial

[oruebel]

What would you like changed or added to the documentation and why?

Once https://github.com/hdmf-dev/hdmf/pull/747 has been released in HDMF, we should update the parallel I/O tutorial accordingly to:

1. avoid having to create an empty DataChunkIterator and use H5DataIO instead
2. avoid having to close and reopen the file
3. Show how this pattern can be used to customize write in the serial case as well

We should also update the following section of the iterative write tutorial https://pynwb.readthedocs.io/en/stable/tutorials/advanced_io/iterative_write.html#alternative-approach-user-defined-dataset-write to use the new functionality and avoid writing a dataset that is too small and then resizing later.

Do you have any interest in helping write or edit the documentation?

Yes.

Code of Conduct

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