docs: additional tutorial data for multiple morph misses `temperature` field

[ycexiao]

Both the old and new manual uses

pdfmorph SrFe2As2_150K.gr . --multiple-targets --sort-by=temperature

to demonstrate how to sorting Rw by assigned field.

However, by running this I get

pdfmorph: error: The requested field is missing from a PDF file header.

According to the old manual section 3.2.1, page 10, the expected .gr should start with

But the data now in tutorial/additionalData/morphsequence/ , it start with

Temperature field is missed.

Also in the manual the corresponding directory is referred as morphMultiple, it seems that it is renamed as morphsequence. I can fix that in the other PR.

Sorting morphs by temperature is a good example. The only problem is that the data we are using doesn't have the temperature field now. I can add them manually, or someone could provide me the correct version of these data.

[ycexiao]

@sbillinge Please see this. I guess the fastest way is to just add the field directly. Is it workable for the repo?

[sbillinge]

Thanks for catching this, great work! Yes, a good fix is simply to update the data-files in this case.

However, it opens up the possibility to make our software better. It is quite common for files to have temperature in the name but not in the header. Let's make an issue to handle "metadata - filenames". There should also be a similar issue in diffpy.utils which would be a better place to put it honestly.

I would also make the error message better. We usually use the approach "what went wrong. How to fix it". The current error message says what went wrong but not how to fix it.

When you fix the docs/directories in the repo, please fix the docs to reflect the directories (which are now in pep8 standard) and not vice versa.