Documentation Link

https://matplotlib.org/devdocs/devel/documenting_mpl.html#building-the-docs

Problem

Latex, graphviz, and inkscape are kind of heavy dependencies to install if you're working on documentation changes that don't depend on latex, graphviz, or inkscape - like most of the gallary and a lot of the tutorials.

Suggested improvement

Can we adopt a sphinx equivalent ofskipif? Two ways of doing this are: (edit: these are both sphinx directives)