Set docstring linewidth to 75 to avoid wrapping in jupyterlab help popup

[joelostblom]

I noticed that I didn't cover the one line chart descriptions in #1866, so adding them in this PR.

Current:

Suggested:

When I did this I noticed that the exact line width that jupyterlab breaks at is 76, not 78, so I updated the autoformatting of the docs as well.

[joelostblom]

I should note that the pep8 recommendation for doscstrings is a line width of 72 so I can change to that if desired. I looked around briefly in the rest of the plotly code and it seems like a both 72 and 75 is used, so either should be fine for consistency within the project. I am happy with either, I just want the docstrings to fit without wrapping in the help dialog boxes.

[nicolaskruchten]

Thanks for this! Let's stick with 75 for now unless we can easily force everything to 72 :)