Latex docs page should describe how to include MathJax

[Helveg]

I can't use any kind of Latex typesetting in Plotly.js. See this codepen taken from the documentation.

[alexcjohnson]

Hi @Helveg - You need to include MathJax, which is not bundled with plotly.js - see https://github.com/plotly/plotly.js/tree/master/dist#to-support-mathjax

Thanks for pointing out that this step isn't described in that docs page - I'll rename the issue and move it to the docs repo.

[moble]

There is now a codepen linked from the docs that loads MathJax. Maybe this could be closed?