BUG: moved get_info from backend.py to _nx_parallel

[Schefflera-Arboricola]

Please do "Squash and merge" while merging this PR

fixes #52

for ref. #27

[dschult]

I don;t think you need to make the additional parameters dict. It is a helpful structure if you already know the parameter names and corresponding docs. But when you are pulling from existing doc_strings on these functions, it is probably easier to just extend the additional_docs string with the parameter descriptions.

That is: you can add the parameter section of the doc_strings to the additional_docs field (leaving additional_parameters blank) rather than parsing and making the dict structure required for additional_parameters`.

[dschult]

This looks good to me. Let’s try it.
The failing test is unrelated.