generalize python example note

[prjemian]

• close DOC: Generalize 'note' on the Python 'Getting started' page #1239

[prjemian]

Belated Happy Birthday wishes to this PR. Please review promptly.

[PeterC-DLS]

A bit more work needed

[prjemian]

Thanks. @rayosborn : Can you assist with these changes?

[rayosborn]

I'll take a look later today

[rayosborn]

It's an improvement but it still needs a little work.

"The NeXus signal="I00" attribute on the :ref:NXdata group identifies I00 as the default y axis for the plot. The axes="mr" attribute on the :ref:NXdata group connects the dataset to be used as the x axis."

Perhaps a sentence should be added after this.

"In the nexusformat version, these attributes are added automatically when calling NXdata(y, x) with the first argument defining the signal and the second the axes. With signals of higher rank, the second argument would be a list of axes."

In the reader section, it says:

"The file reader, :ref:simple_example_basic_read.py <Example-Python-Reader>, opens the HDF5 we wrote above, prints the HDF5 attributes from the file, reads the two datasets, and then prints them out as columns. "

Actually, the nexusformat version prints the whole file as a tree.

[prjemian]

initial table

Added nexusformat comments:

output is shown for each in tabs

[prjemian]

@PeterC-DLS @rayosborn - Ready for review.