Math rendering issue advice

[brownsarahm]

In the review of intro to deep learning, we encountered a math rendering issue that is not a problem with the template, but probably a macos issue that the reader of a site can resolve for themself, but does not appear to have an infrastructure side solution:

1. Right-click on some of the misrendered MathJax.
2. Click on "Math Settings".
3. Click on "Math Renderer".
4. Click on "Common HTML".

For that lesson, they put in a PR for an instructor note

It might be worth documenting that here for developers of future lessons too?