Particle Position Reading: Fix Python Example

[skuschel]

Fix the outdated record reading example (python).

[ax3l]

ah, interesting. I never used .value on h5py.Dateset types before. It returns the numpy.ndarray directly, cool. (Docstring: Alias for dataset[()])
yes, that is way more general then the example assuming a 1D array [:]. Alternatively, [()] would be the same says the docstring.

[ax3l]

@skuschel looks good to me, I let @RemiLehe have a look too and then we can merge it.

Thanks a lot for fixing the example, that is great! ✨

[RemiLehe]

The corrections are fine with me. @skuschel : Thanks a lot for spotting and correcting these mistakes !
@ax3l : You can merge it.