Add mathjax integration

[DanOvando]

Expected Behavior

Great theme, thanks! I'm writing an academic blog using blogdown and hugo-future-imperfect. Posts usually involve at least a few mathematical equations, so wanted to build that capacity into this theme

Current Behavior

Equations do not seem to be currently supported, and I couldn't find any reference to equations in the documentation, current issues, or pull requests. So, this will allow users of the theme to easily integrate equations in their blogs.

Possible Solution

I simply integrated the steps for integrating mathjax from the blgodown default theme. I'm very new to hugo but it works on my end, branch with mathjax integration here. Should be ready for a pull request if you feel this feature is worth exploring

Steps to Reproduce or Template with Error (for bugs)

Context

Sometimes despite our best intentions we're forced to write equations in blogs, hopefully this helps other users accomplish this using your theme

Your Environment

Hugo Version:
0.36
Browser:
Firefox

Desktop or Mobile:
Desktop
Link to your project:
https://github.com/DanOvando/hugo-future-imperfect/tree/add-mathjax

[DanOvando]

mathjax

[pacollins]

Feel free to make the PR and we can review from there.

Thanks for your contribution!