Add a flowchart to the categorical plots tutorial

[mwaskom]

This should show the sequence of questions one asks oneself while deciding which plot type to use. This basically exists in the narrative of that page already, but it would be good to have in a more visual form.

[noahtf13]

I'd love to tackle this!

It looks like the docs are generated through .ipynb files. Were you thinking of having a flowchart that was generated in python (ex. pyflowchart package) or simply having a image read in from a markdown cell?

If I go the image route is there somewhere on the repo it should live or should it be hosted outside of this repo?

[mwaskom]

The idea i had in mind here was something like the scikit-learn flowchart.

In terms of documentation infrastructure, I think I would like to avoid adding another dependency to the doc buildchain, and also would like to avoid checking a large rasterized image into the repo. Generating a vector graphics image on the fly would be ideal, and having the doc source as notebooks provides a lot of flexibility in how to accomplish that.

[noahtf13]

Thanks for detailed response, I'll get a PR going soon.

[itsdivya1309]

Is this issue assigned to someone? I am new to open-source and would like to make my first pull request through this issue.